Osaka lit the Olympic cauldron on Friday and was widely hailed as the 'face of the Games', with enormous expectation that she would go on to triumph for hosts Japan.
The early exit of world number one Ash Barty seemed to help her case, but Osaka lost 6-1 6-4 to her Czech opponent in an hour and eight minutes.
Nadal is widely expected to retire from tennis later this year, with the Olympics set to represent his swansong at Roland-Garros, where he has won 14 French Open titles.
He will play in both the singles and doubles tournaments, partnering current French Open and Wimbledon champion Carlos Alcaraz for the latter competition.
Nadal and Alcaraz will face Argentina's fourth-seeded pair Maximo Gonzalez and Andres Molteni in a difficult first-round matchup in the doubles tournament.
Nadal is one of just two players to have won Olympic gold in both singles and doubles since the sport returned to the Games in 1988, doing so at Beijing 2008 (singles) and Rio 2016 (doubles) – Nicolas Massu triumphed over both events at Athens 2004.
In the singles, Nadal will take on Hungary's Marton Fucsovics in the opening round, and the prize could be a second-round date with Djokovic, who faces Australian Matthew Ebden first.
They are on the same side of the draw as third seed Alexander Zverev, who faces Jaume Munar first, and seventh seed Taylor Fritz, who opens against Alexander Bublik.
On the opposite side of the bracket, Alcaraz will start his campaign against Hady Habib, with Britain's Cameron Norrie a potential second-round opponent.
Fourth seed Daniil Medvedev faces Rinky Hijikata in his first match, while fifth seed Alex de Minaur is a potential quarter-final opponent for Alcaraz.
Britain's Andy Murray withdrew from the singles event to concentrate on his doubles bid alongside Dan Evans on Thursday, and the duo will face Kei Nishikori and Taro Daniel of Japan first.
Should they advance, home favourites Arthur Fils and Ugo Humbert could await in round two, with Taylor Fritz and Tommy Paul potential quarter-final foes, though the Americans will have to overcome Canada's Milos Raonic and Felix Auger Aliassime to get that far.
Murray and Evans cannot face Nadal and Alcaraz until the final.
Iga Swiatek is the strong favourite in the women's draw, having won four French Open titles on the Paris clay. Romania's Irina-Camelia Begu is her round-one opponent.
On her same side of the draw, there is a huge round-one clash between Naomi Osaka and 2016 silver medallist Angelique Kerber, who announced on Thursday that she will retire after the Games.
Elena Rybakina and Danielle Collins are also on that side of the draw, while Coco Gauff starts against Ajla Tomljanovic on the opposite side of the bracket.
Four-time grand slam champion Osaka, now ranked at world number 95, lost in straight sets to Germany's Angelique Kerber on Court Philippe-Chatrier in Paris.
Former world number one Osaka returned to tennis earlier this year after giving birth in July 2023.
Now she hopes she can climb back up the rankings by watching others on the tour, and world number one Swiatek has been high on her list.
"I was stalking Iga. I was watching her practice at the Olympics, and for me, that's something I want to do more, watch the great players, because there's always something I can pick up on," Osaka told reporters ahead of the Canadian Open.
"I know she has one of the best footwork skills on the WTA. I'm just trying to copy a little bit."
The Japanese player found her Olympics experience more enjoyable than three years ago at her home Games, where she lit the Olympic flame.
"I would say in Tokyo [2020], I was definitely really stressed. In Paris, I felt a lot more fun. And obviously there were spectators there, so it was a lot different," reflected the 26-year-old.
"In Paris, I felt a lot more fun. And obviously there were spectators there, so it was a lot different. But I didn't stay in the village, so that is something that I regret a little bit, not to have the full experience. Overall, I think it was it was fun. Hopefully, I can play in LA [in 2028]."
Osaka has naturally faced challenges in her return to sport following pregnancy, which has made her presence at the Olympics a year on from giving birth impressive in itself.
"Honestly, after pregnancy, I wasn't really sure how my movement would be," said Osaka.
"I remember being on the track at UCLA [University of California, Los Angeles] and almost crying in frustration because I felt like I couldn't run as fast as I wanted to.
"It felt like I was in a body suit that was not performing the way I wanted. Now, to be here, is a really incredible achievement."
Having a daughter has also given Osaka a new outlook on her sport.
"I lost in the Olympics, I was, of course, really devastated," she explained. "But I was just surrounded by my team.
"Then I went back home, and I saw my daughter, and she's just happy to be alive. She's happy that I'm her mom and it just gave me a lot of motivation.
"I feel like when I was younger I was searching for my purpose in life. The way I grew up, my only purpose was tennis. Then obviously taking the year that I had as a break, it let me see that there are so many different things in life and it's a beautiful world."
Osaka has not played since withdrawing from the French Open after revealing she would skip press conferences at Roland Garros as "people have no regard for athletes' mental health".
The four-time grand slam champion from Japan revealed she had suffered "long bouts of depression" since winning the US Open in 2018.
Osaka says she has not changed her stance on press conferences and feels she had been unfairly scrutinised.
The world number two wrote in Time magazine: "I communicated that I wanted to skip press conferences at Roland Garros to exercise self-care and preservation of my mental health. I stand by that.
"Athletes are humans. Tennis is our privileged profession, and of course there are commitments off the court that coincide. But I can't imagine another profession where a consistent attendance record [I have missed one press conference in my seven years on tour] would be so harshly scrutinised.
"Perhaps we should give athletes the right to take a mental break from media scrutiny on a rare occasion without being subject to strict sanctions.
"In any other line of work, you would be forgiven for taking a personal day here and there, so long as it's not habitual. You wouldn't have to divulge your most personal symptoms to your employer; there would likely be HR measures protecting at least some level of privacy.
"In my case, I felt under a great amount of pressure to disclose my symptoms - frankly because the press and the tournament did not believe me. I do not wish that on anyone and hope that we can enact measures to protect athletes, especially the fragile ones.
"I also do not want to have to engage in a scrutiny of my personal medical history ever again. So I ask the press for some level of privacy and empathy next time we meet."
Osaka is feeling the benefits of a break and is relishing representing her country in the Olympics on home soil in Tokyo.
"After taking the past few weeks to recharge and spend time with my loved ones, I have had the time to reflect, but also to look forward," the 23-year-old said.
"I could not be more excited to play in Tokyo. An Olympic Games itself is special, but to have the opportunity to play in front of the Japanese fans is a dream come true. I hope I can make them proud."
In her final tournament, the German kept her hopes of going out on a high alive, getting a 7-5 6-3 victory in just 69 minutes at the end of a rainy opening day at Roland Garros.
Osaka started strongly, racing into a 3-1 lead, but Kerber fought back and eventually got the vital break in the penultimate game of the set to edge in front.
The two were evenly matched again at the start of the second, but Osaka struggled to maintain her high level and lost her serve twice at the end as Kerber's four-game winning run carried her over the line.
Kerber will now face Jaqueline Cristian of Romania in the second round.
Data Debrief: Going for gold
Kerber won a silver medal in singles at Rio 2016, and she is looking to sign off her glittering career by going one better in Paris.
She asserted her dominance in the second set, particularly, winning 13 of 14 points when she got her first delivery into play.
Kerber also bows out holding a 5-2 head-to-head record over Osaka, who once again struggled on clay.
Osaka lit the Olympic cauldron on Friday and was widely hailed as the 'face of the Games', with enormous expectation that she would go on to triumph for hosts Japan.
The early exit of world number one Ash Barty seemed to help her case, but Osaka lost 6-1 6-4 to her Czech opponent in an hour and eight minutes.
Osaka played a dismal opening set but then looked to have raised her game a notch in the second, establishing an early break.
However, that did not herald a full-blown fightback as former French Open runner-up Vondrousova soon got back on level terms and forced Osaka to serve to stay in the contest.
From 15-40, Osaka saved two match points, but Vondrousova soon had a third opportunity and her spirited defence won out.
Osaka flung a backhand wide this time and Vondrousova had her prized scalp, securing a place in the quarter-finals at the expense of the world number two.
It was an untidy performance from Osaka who made 32 unforced errors to just 10 from Vondrousova.
This was Osaka's first tournament since pulling out of the French Open at the end of May, in the wake of a first-round win. She cited depression and anxiety issues in Paris after announcing she would not take part in news conferences during the tournament.
Postponed due to the coronavirus pandemic, the Games are scheduled to begin on July 23 this year.
This year's Australian Open will begin on February 8 after players quarantined ahead of the first grand slam of the year.
Osaka said she would be prepared to do it all again if it meant she got the chance to play at the Olympics.
"Honestly, my concern isn't the athletes. The way that I feel is I will stay in my room for two weeks to play the Olympics. I missed out on the last one," the Japanese star told a news conference on Sunday.
"Playing in Tokyo would be very special to me. My concern would be the general safety of everyone else because you're opening the country. Everyone is flying in from different places. I would just want the public to feel safe.
"I feel like the athletes definitely would want to play, but I would want the public to feel safe."
Doubts have also been cast over the Olympics going ahead this year due to COVID-19.
Osaka, a three-time major champion, said while people she had spoken to were excited, some were worried.
"For me the people that I've spoken to, they're really excited about it, but they're concerned because, I don't know, there's just like so many different people entering. I don't know," she said.
"For the people I've talked to, they said as long as everyone is safe, as long as Japan is getting better and not worse, then it should be okay.
"But for me, hmm, don't quote me on that."
Ahead of the Australian Open, Osaka is playing the Gippsland Trophy, where she will face either Alize Cornet or Ajla Tomljanovic in the second round.
The 24-year-old gymnastics icon revealed she was “dealing with things internally” after a disappointing performance on the vault.
Biles posted the lowest score of the first rotation on Tuesday as she landed awkwardly after failing to execute an Amanar, while only completing a Yurchenko 1.5 twist.
After she subsequently withdrew, Team USA had to settle for a silver medal behind the Russian Olympic Committee while Great Britain completed the podium.
Biles admitted that she was "fighting demons", explaining: "I just don't trust myself as much as I used to. I don't know if it's age. I'm a little bit more nervous when I do gymnastics. I feel like I'm also not having as much fun."
She added: "I say, 'put mental health first'. Because if you don't, you won't enjoy sport and won't succeed as much as you want to.
"So it's okay sometimes to sit out the big competitions to focus on yourself, because it shows how strong a competitor and person that you really are, rather than just battling through it."
OSAKA STUNNED
The big names continue to tumble in the women’s singles tennis event, with second seed Naomi Osaka defeated in straight sets.
The home favourite, who lit the Olympic cauldron on Friday, was denied a place in the quarter-finals after being ousted 6-1 6-4 by world number 42 Marketa Vondrousova.
This event marked Osaka’s first competitive tennis in two months since her early withdrawal from the French Open at the end of May, citing mental health issues.
The world number two is the latest of the big names to fall at the Tokyo Games, with top seed Ash Barty and third seed Aryna Sabalenka also suffering early exits.
"Of course, it's one of the biggest wins of my career," Vondrousova said. "Naomi is a great player, so I knew it would be a tough match.
“I'm very happy with my play. I played amazingly in the first set, and then the second set was really tough. I'm just happy to be through."
ARGENTINA RECOVER TO SEE OFF SPRINGBOKS
Argentina recovered from a dreadful start to beat South Africa and book their place in the rugby seven semi-finals.
Trailing 7-0 after just under two minutes, the Pumas were then reduced to six men when Gaston Revol - who was reduced to tears - was shown a straight red card.
Nevertheless, they demonstrated tremendous resilience and character before eventually running out 19-14 winners.
Argentina will play Fiji in the last four after the reigning Olympic champions swept Australia aside 19-0.
Great Britain stormed back from 21-0 down to beat the USA, scoring four tries to secure a dramatic 26-21 victory.
Team GB will play New Zealand, who eased to a 21-10 success over Canada.
Osaka, who lit the flame at Friday's opening ceremony, had won her opening two matches but bowed out in straight sets, with Vondrousova reaching the quarter-finals.
In the first set, Vondrousova dominated on her first serve and broke three times, before the Japanese hit back with an early break in the second. But the Czech fought back to win, with Osaka finishing with 32 unforced errors to just 10 by her opponent.
"Of course it's one of the biggest wins of my career," Vondrousova said. "Naomi is a great player, she has so many grand slams, so I knew it would be a tough match. I'm very happy with my play. I played amazingly in the first set, and then the second set was really tough. I'm just happy to be through."
World number two Osaka joins top seed and Wimbledon champion Ash Barty in being eliminated early at the Tokyo Games.
In the men's singles second round, fourth-ranked Greek Stefanos Tsitsipas eased past American Francis Tiafoe 6-3 6-4, avenging a shock Wimbledon defeat.
DUFFY DELIGHT
Flora Duffy won Bermuda's first-ever Olympic gold medal with victory in the women's triathlon on Tuesday at Odaiba Marine Park.
The four-time Olympian failed to finish in Beijing, came 45th in London and improved to eighth in Rio de Janeiro.
Duffy took the Tokyo title in a time of one hour, 55 minutes and 36 seconds, finishing more than a minute ahead of Britain's Georgia Taylor-Brown who took silver, with USA's Katie Zaferes claiming bronze.
“It's always been my dream to race at the Olympics and be a professional athlete with the goal of being an Olympic champion," Duffy said.
"That's not the easiest thing to do regardless of where you're from. Bermuda is a small country, but it's really passionate about its sport.
“I'm so grateful that I could achieve a personal dream here of winning an Olympic medal, but this is bigger than me, this is going to inspire the youth of Bermuda and everyone back home that competing on the world stage from a small island is really possible."
The 33-year-old broke clear in a group of seven early in the bike stage, before dominating the 10km run.
Bermuda, which has a population of just over 70,000, had only claimed one medal previously in Olympic history, a bronze in 1976.
MCKEOWN BREAKS OLYMPIC RECORD
Australia secured a second gold medal in the pool as Kaylee McKeown broke the Olympic record in the women's 100m backstroke.
McKeown won in 57.47, finishing ahead of Canada's Kylie Masse by 0.25 seconds, with USA's Regan Smith taking bronze. Masse had led at the turn.
In the men's 100m backstroke, Russian Olympic Committee claimed a one-two finish as Evgeny Rylov edged out countryman Kliment Kolesnikov, who holds the 50m world record. Ryan Murphy, who is the world record holder across 100m, claimed bronze.
Great Britain's Tom Dean won the men's 200m freestyle by 0.04, marginally ahead of compatriot Duncan Scott, with Brazil's Fernando Scheffer coming in third. The result meant two British male swimmers stood on the same Olympic podium for the first time since 1908.
World record holder Lilly King finished third as US teenager Lydia Jacoby triumphed in the women's 50m breaststroke. South Africa's Tatjana Schoenmaker claimed silver.
CHINESE PAIR ON TARGET
China claimed another gold medal in the final of the 10m air pistol mixed team at the Asaka Shooting Range.
China's Ranxin Jiang and Wei Pang won 16-14 over Russian Olympic Committee pair Vitalina Batsarashkina and Artem Chernousov.
Ukraine duo Olena Kostevych and Oleh Omelchuk won the bronze by beating Serbia.
The 10m air rifle mixed team bronze and gold medal matches were taking place later on Tuesday.
AUSSIES SINGING IN MEN'S HOCKEY
World number two side Australia knocked off reigning Olympic gold medallists Argentina 5-2 in the men's hockey group stage.
Australia claimed their third consecutive victory and top Group A, this time being aided by two goals from Blake Govers.
The Kookaburras have only won one Olympic gold despite often being a dominant side in men's hockey and are one of the favourites to triumph in Tokyo.
Japan and New Zealand, who both previously lost to Australia, drew 2-2 in the other Group A game.
In Group B, world number four India won 3-0 over Spain, while fifth-ranked Germany beat Great Britain 5-1.
The top contenders spent much of Monday's race biding their time, with all the favourites in the mix following the swim and bike legs, but Blummenfelt drove the pace on the final leg.
When the lead group winnowed down to himself, Great Britain's Alex Yee and Hayden Wilde of New Zealand, Blummenfelt urged the 23-year-olds to keep the hammer down – then ran away from them in the end.
One last kick over the final kilometre put Blummenfelt atop the podium, with Yee taking silver and Wilde bronze.
"We were like 10 guys in the running lead and when he picked up the pace I saw that we were down to four and I tried to get [Yee] motivated to keep the pace," Blummenfelt told reporters.
"I said, 'Guys, we have a medal now, keep the gas on,' and I think that for Alex and Hayden this is a great moment to get an Olympic medal, too."
Yee's compatriot Jonathan Brownlee, who won silver in the event in Rio and bronze in London as his brother Alistair took gold in both races, finished fifth on Monday.
"I told myself last night that all I can do is try my hardest and before that, prepare," Brownlee said. "I did everything I could, I got ready for the heat, I trained as hard as I could, had a great team around me and that's all you can ask.
"I think I've been very, very fortunate in my two Olympic Games, I've had two medals. It's hard to perform and I've performed well in three."
'NERVOUS' OSAKA KEEPS ROLLING
Playing for the second consecutive day, second-seed Naomi Osaka showed no signs of fatigue as she cruised to a 6-3 6-2 second-round victory over Switzerland's Viktorija Golubic on Sunday.
Japan's big hope Osaka had to play back-to-back after having her schedule altered following the honour of lighting the Olympic cauldron Friday, and the other top women in action looked just as strong after a day off Sunday.
"Honestly, I feel like I was a bit more nervous before the match," Osaka told reporters. "I felt a lot of butterflies, but I think as I started playing and feeling more comfortable, I knew that no matter what it would be a great match."
After pulling out of the French Open before the second round and skipping Wimbledon, the four-time grand slam winner has not had much match time over the last two months, but her goal in Tokyo remains the same.
“It would mean a lot to win gold here, but I know it's a process," she said. "I know these are the best players in the world, and honestly I haven't played in a while, so I'm trying to take it one notch at a time.
"All in all, I'm just really happy to be here. I haven't been in Tokyo for a couple of years."
In other early matches, seventh-seeded Garbine Muguruza of Spain rolled past China's Wang Qiang 6-3 6-0, while eighth seed Barbora Krejcikova had a tougher time with Canada's Leylah Annie Fernandez before moving on 6-2 6-4 and 11th seed Anastasia Pavlyuchenkova defeated Anna-Lena Friedsam 6-1 6-1.
MACNEIL EARNS CANADA'S FIRST GOLD
It took Margaret MacNeil a few moments to realise she had won Canada's first gold medal of the Tokyo Games.
The 21-year-old usually wears contact lenses but does not put them on when she is in the pool, so she had to focus to see her name atop the scoreboard after the 100m butterfly at the Tokyo Aquatics Centre.
"I like to check the scoreboard pretty quickly, but it's hard just because I don't have contacts," she said. "It does take me a minute to read the scoreboard, so I was just trying to squint and see where I came."
Her vision problems may have been a benefit during the race, which saw her edge China's Zhang Yufei by 0.05 from lane seven.
"I could hardly see anyone on the far side of the pool, which I think helped me a lot, because I was able to just focus on my own race," MacNeil said. "I just put my head down and tried to get to the wall as fast as possible. I'm really glad it all came together."
While MacNeil took the first gold medal in the pool Monday, her win was overshadowed by later events.
Great Britain's Adam Peaty defended his Olympic title in the 100m breaststroke, while Ariarne Titmus of Australia dethroned the reigning champion Katie Ledecky in the 400m freestyle.
In the final medal event of the day, Caeleb Dressel – Michael Phelps' heir apparent – and the USA won the 4x100m freestyle relay by 1.14 seconds over Italy.
UPSETS ABOUND IN FENCING
Three of the top six women in the world were eliminated early in the women's sabre competition Monday.
Top-ranked Olga Kharlan of Ukraine, twice a bronze medallist, fell to Yang Hengyu of China 15-12 in the round of 32 to end her hopes of a third straight medal.
Fourth-ranked Shao Yaqi of China and world number six Anne-Elizabeth Stone of the USA went out in the same round.
Sofia Velikaya of Russia, who took silver in Rio, remains alive heading into the quarter-finals later Monday along with 2016 fourth-place finisher Manon Brunet of France.
REIGNING CHAMPIONS FIJI OPEN RUGBY SEVENS PLAY
Reigning gold medallists Fiji rallied in the second half to defeat Japan 24-19 in a rematch of the Rio 2016 semi-finals.
Fiji trailed 19-12 but fought back through a pair of tries and a conversion from substitute Waisea Nacuqu in the final four minutes.
The team they beat for gold five years ago, Great Britain, opened play with a flourish, thrashing Canada 24-0, while New Zealand crushed South Korea 50-5.
Fourth-place finishers in 2016, South Africa defeated Ireland 33-14 while Argentina beat Australia 29-19 and the United States edged Kenya 19-14.
In a stacked women's draw, world number one and Wimbledon champion Barty has a tough opening assignment and could face French Open finalist Anastasia Pavlyuchenkova, the 13th seed, as early as round three.
Spectators may not be in attendance at Tokyo venues for the Olympics but Japanese fans will be rooting for Osaka, who returns to action after a two-month hiatus with the four-time grand slam winner having spoken openly about mental health and anxiety issues.
Viktorija Golubic or Maria Camila Osorio Serrano would await Osaka if she can get through round one, but a dream final with Barty is no shoo-in given 15 of the world's top 20 on the WTA Tour are in action including each of the nine leading the race for the 2021 WTA Finals.
Aryna Sabalenka (3), Elina Svitolina (4), Wimbledon runner-up Karolina Pliskova (5), Iga Swiatek (6) and Garbine Muguruza are all featuring in Tokyo.
The men's side has been hit by a spate of withdrawals, with Rafael Nadal, Roger Federer and Dominic Thiem among those not playing in the Japanese capital.
The main talking point surrounds whether the all-conquering Djokovic can continue his march towards a calendar Golden Slam – a sweep of all four majors and an Olympic gold in the same year.
Any notion of a free ride for the Serbian is wide of the mark, though. His side of the draw could see him come up against Andrey Rublev (5), Alexander Zverev (4) and Hubert Hurkacz (7), while Stefano Tsitsipas (3) – beaten by Djokovic in the French Open final – and Daniil Medvedev (2) are among the potential final opponents.
Andy Murray, gold medal winner in 2012 and 2016, faces Canada's Felix Auger-Aliassime in a tricky first-round match.
The world number one fell at the first hurdle at Arianke Tennis Park, going down 6-4 6-3 against her Spanish opponent.
There were no such problems for Naomi Osaka; the home favourite overcame China's Zheng Saisai in straight sets.
BARTY TO KEEP FIGHTING FOR GOLD MEDAL
Crowned Wimbledon champion this month, Barty was unable to build on that momentum; amassing a whopping 55 errors.
World number 48 Sorribes Tormo took full advantage to set up a second-round showdown with France's Fiona Ferro.
Osaka was given the honour of carrying the torch on the short final leg at the Japan National Stadium before walking the steps to light the flame and end the opening ceremony.
The four-time grand slam champion is the face of the Tokyo Games in her home country, creating extra pressure on her shoulders as she bids to strike gold.
Djokovic appreciates the absences of legendary names Roger Federer and Rafael Nadal is a blow, but he believes Osaka's presence is crucial for tennis in the battle for media coverage at the Games.
"It cannot be better for our sport, you are representing yourself, your country but also your sport in the Olympic Games, you're trying to get the hype and the attention towards our sport as much as you possibly can, so we're all contributing to that in the Olympic Village," Djokovic said when asked about Osaka's role in Friday's ceremony.
"There's a lot of attention towards the tennis players which is great, from the other athletes which is very nice to see, very nice to experience.
"Obviously you don't have Roger or Rafa. They are big stars and legends of our sport, but still there's quite a lot of great athletes, top players. Naomi is a home favourite and a lot of eyes are on her.
"Being at home playing is a lot of pressure, but it's great for our sport just in general to see that there's a lot of attention towards it."
Djokovic was speaking after overcoming Hugo Dellien with ease in his opening outing in the men's singles tournament, the Serbian triumphing 6-2 6-2 in just over an hour.
The quick win allowed the recently crowned Wimbledon champion to avoid staying out for too long in the Tokyo heat, an issue that led to Daniil Medvedev calling for matches to be pushed back to later in the day, allowing players to compete during the evenings when the temperatures have dropped.
"I agree with him 100 per cent," Djokovic said of Medvedev's suggestion. "I actually asked as well.
"My team captain, Viktor Troicki, was speaking to the referee a couple of times. To be honest, I don't understand why they don't start matches at say 3pm.
"I've heard for tennis there is some kind of curfew they have to finish at midnight, but if that's the case, I've just finished the last match and it's not even 5pm, we still have seven hours to play.
"They have lights on all the courts, they're going to make life much easier for all of us tennis players, I just don't understand why they don't move it.
"It's actually for the television broadcasters even better, because the later you play, the better it is for the United States and the time zones in Europe.
"I don't know, maybe the ITF (International Tennis Federation) can give you a better answer to why they chose to be played in the middle of the day. I doubt they will change the decision, but we're hoping that they will."
The only men to have won each of the singles majors across their careers, plus Olympic gold, are Andre Agassi and Rafael Nadal, and now Djokovic aims to move to the brink of winning all five in his remarkable 2021 season.
Fresh from dominating at Wimbledon, and with the Australian and French Open titles already in the bag, Djokovic heads into the Tokyo Games as a red-hot favourite, seeking to set himself up to complete a historic campaign at the US Open.
Naomi Osaka will enter the Games with almost as much expectation behind her too, the reigning US Open and Australian Open champion eyeing glory for hosts Japan.
But tennis has thrown up a host of shock results in its short Olympic history. Here, Stats Perform looks at the sport's place in the Games.
WHO'S IN, WHO'S OUT, AND WHAT DOES ALL THIS MEAN?
Serena Williams, Roger Federer and Rafael Nadal have all opted out of the Olympics.
Williams made her mind up prior to suffering a leg injury at Wimbledon, although she is already a member of the career Golden Slam club.
Federer reached his decision after revealing he also suffered a physical setback at the All England Club, and Nadal elected to take a two-month break after relinquishing his French Open title.
Don't expect to see them again at the Olympics, given Williams and Federer will be pushing 43 by Paris 2024, and Nadal will be 38. Federer won a doubles gold with Stan Wawrinka in 2008, but his singles peak was the silver medal he earned in 2012, Andy Murray crushing Swiss hopes in the final at Wimbledon.
Dominic Thiem, Bianca Andreescu, Nick Kyrgios, Simona Halep, Angelique Kerber, Victoria Azarenka and Denis Shapovalov are among other confirmed absentees, with fitness issues a factor for some, less so for others.
The COVID-19 crisis is a mitigating factor in why so many stars are staying away, and directly responsible in the case of some players, such as Britain's Johanna Konta and Dan Evans, who both tested positive recently.
But tennis was only fully restored to the Olympic programme in 1988, after being dropped post 1924, and if players are seen to be favouring the grand slams over the Games, that is not such a great look for the sport.
At a time when the International Olympic Committee has shown it is willing to shake up the sports on its programme, tennis could perhaps do with a headline-making Tokyo 2020.
Murray, the two-time defending men's champion, will target an improbable hat-trick. A hat-trick for the injury-hit former world number one would be a sensation, and Osaka landing gold in the women's tournament would surely be one of the great moments of the Games.
DJOKOVIC FOLLOWING IN THE FOOTSTEPS OF GRAF
When Steffi Graf beat Gabriela Sabatini in the women's singles final at Seoul, it completed what we know now as the calendar 'Golden Slam'. She had already won the Australian Open, French Open, Wimbledon and the US Open, and the feat of the then 19-year-old West German has yet to be repeated.
Now Djokovic is three-fifths of the way to a similar clean sweep of the majors and the Olympics, with the US Open getting under way on August 30 in New York.
He teetered on not going to Tokyo, and perhaps he is to some extent endangering his chances at Flushing Meadows by spending more time travelling and enduring bubble life, while others rest up.
But Djokovic is a fiercely proud Serbian and could not resist a great chance of winning gold for his country. He landed bronze at the 2008 Games in Beijing but in 2012 he lost to Juan Martin del Potro in the bronze-medal match, and a cruel draw at Rio four years later saw him assigned Del Potro in the first round.
Top seed Djokovic bowed out in two tie-breaks to the powerful Argentinian, describing the outcome as "one of the toughest losses in my career".
There is no danger of a hat-trick of defeats to Del Potro, which may help Djokovic. Del Potro has been battling for two years to get back to fitness, undergoing four rounds of right knee surgery in a bid to get back on tour.
RAISING THE BAR AT THE OLYMPICS
How the Olympic village functions in Tokyo will be distinctly different to at previous Games, given the pandemic restrictions in place that could be a real buzzkill.
But in the past there have been countless cases of athletes becoming inspired by their surroundings and going on to perform above their usual level.
It can be a party village, and it can also be an eyebrow-raising experience as global superstars rub shoulders with competitors who might struggle for recognition in their home towns. More than anything, the shared team experience, fighting for a collective cause, can make a middling athlete believe they can be great.
Monica Puig was a massive tennis outsider in 2016 but the then world number 34 won the women's singles, stunning Angelique Kerber in the final after beating Petra Kvitova and Garbine Muguruza en route. That gave Puerto Rico their first ever Olympic gold medal.
In 1992, a tournament that featured the likes of Pete Sampras, Jim Courier, Stefan Edberg and Boris Becker finished with a staggering final match-up of Marc Rosset versus Jordi Arrese, who in his home city of Barcelona was edged out 8-6 in the fifth set by the Swiss world number 43. Nobody would have predicted that head to head for gold.
Similarly, at Athens 2004, Nicolas Massu beat Mardy Fish in the gold medal match of a tournament that featured Federer, Andy Roddick, Carlos Moya and Tim Henman.
In the 1996 Atlanta Games, Lindsay Davenport, who had just turned 20, took inspiration from being the daughter of an Olympian, with dad Wink having played volleyball for the United States at Mexico City in 1968.
Davenport was beginning to make an impact on the WTA Tour but was only the ninth seed at the Olympics, yet she swept through the rounds before sinking Arantxa Sanchez Vicario 7-6 (10-8) 6-2 in the final.
"It's like one of those things I look back on and I'm like, 'Was that me?'," Davenport told The Tennis Podcast last year.
"It doesn't seem like it was real. I'd made the transition to the pro tour pretty well, but I liked hanging out between eight and 16 in the rankings. I was very insecure, unsure of what could I do. I liked doing well but I wasn't sure I wanted to do too well because it seemed really overwhelming to be one of those top players.
"Here I go at 20 years old to Atlanta for two or three weeks, in a setting that seemed so comfortable. Look at all these athletes, you have all different shapes and sizes, you have players that are really working hard but have so much in common and you get to hang out with them, breakfast, lunch, dinner in the village."
Davenport was a future world number one and three-time grand slam singles champion, but at this point in her career being an American at an Olympics in the United States was just a thrill.
"You're sharing this with your team-mates who are some of my best friends in Mary Joe Fernandez, Monica Seles. It was the best time ever," she said.
"By the time the tournament actually started we were like, 'Yeah, I'll go play my match and then we'll go back to the village and we'll hang out', and everything went so fast in those few weeks.
"And there I was left standing, winning at the end because I was so incredibly happy and excited with everything that was going on. I kind of forgot what was my job.
"When it became a reality of even just making the team in '96, it was so huge also for my family with having a second generation Olympian."
The surprising 6-1 6-4 loss that a lacklustre Osaka suffered on Tuesday could be explained away by the fact the 23-year-old had not played any competitive tennis since pulling out of the French Open at the end of May.
All the same, it was a major upset as world number 42 Vondrousova took out the highest remaining seed in the draw – the Japanese star who lit the Olympic cauldron on Friday.
Osaka's exit, after previous shock defeats for top seed Ash Barty and number three Aryna Sabalenka, has raised the prospect of a shock champion, just as occurred five years ago at the Rio Games when Monica Puig of Puerto Rico caused a sensation.
Now at the quarter-final stage, there is one former grand slam champion left in the field and two finalists at that level, but it really looks like anyone's title.
VONDROUSOVA SENSES AN OPPORTUNITY
It was remarkably straightforward for Vondrousova at Ariake Tennis Park, as she cruised through the opening set and soon reeled in Osaka's early break in the second.
Osaka saved two match points when serving to stay in the contest, but not a third, planting a backhand wide.
Considering Vondrousova reached the French Open final two years ago, in front of packed grandstands rather than the empty seats in Tokyo, it was no surprise she hesitated when asked whether this win over Osaka was the biggest of her career. It probably doesn't have that cachet, good a win though it was.
"Of course it's one of the biggest," Vondrousova said.
"Naomi is a great player, she has so many grand slams, so I knew it would be a tough match. But I'm just very happy with my play. I played amazingly in the first set, and then the second set was really tough. I'm just happy to be through.
"I think she was struggling a bit with my serving. Also, I use drop-shots very well. I'm just very happy with my game today."
She faces Spain Paula Badosa next and said: "It's very open now. I think every girl is playing really well. Now it's the quarter-final, so we'll see."
HAS SVITOLINA'S TIME ARRIVED?
A fixture in the top 10 over recent seasons, Svitolina has been unable to transfer her regular tour form onto the major stage on a consistent basis.
Maybe the Olympics will be a platform towards success on that stage, with Svitolina now the highest seed remaining in the draw, at number four. The Ukrainian is also on a high on the personal front, having married French tennis star Gael Monfils shortly before heading to Tokyo.
Two semi-finals, at Wimbledon and the US Open in 2019, have been her deepest runs in the majors, and this season has been one of diminishing returns, with a fourth-round run in Australia followed by a third-round Roland Garros exit and a round-two loss at Wimbledon.
Svitolina beat Maria Sakkari of Greece 5-7 6-3 6-4 on Tuesday, setting up a quarter-final against Italian Camila Giorgi who won 6-4 6-2 against Wimbledon runner-up Karolina Pliskova.
"I don't think I'm a favourite because there are lots of good players here and everyone is quite equal," Svitolina said.
A MUG SHOT?
Should Spain's Garbine Muguruza be considered the favourite from this point? With French Open and Wimbledon titles in her trophy room, Muguruza has shown she has what it takes to triumph on a big stage, and a clinical 6-4 6-1 win over Belgian Alison Van Uytvanck on Tuesday was just the job.
She goes on to face Elena Rybakina of Kazakhstan, who edged past Croatian Donna Vekic.
Belinda Bencic of Switzerland caused a surprise by ousting the in-form reigning French Open champion Barbora Krejcikova, springing a 1-6 6-2 6-3 win that means there will be no repeat of the Roland Garros final in the quarter-finals.
That had been on the cards, but Bencic will be the player who takes on Anastasia Pavlyuchenkova for a place in the final four.
Pavlyuchenkova scored an impressive 6-1 6-3 victory over Sara Sorribes Tormo of Spain, the player who knocked out Barty in round one.
Russian Olympic Committee's Pavyluchenkova is looking to harness the form that took her to a maiden slam final, describing her Paris run as "a great experience to have".
"But every week is a new week and this is a new event," said the 30-year-old. "The Olympic Games is a very special event. It's different. It's nothing like the others."
Japan's big hope for gold will play China's Zheng Saisai in her opener at the Ariake Tennis Park.
The match was billed to be first on the centre court at 11:00 local time on Saturday, only for Games organisers to announce it has been moved back by a day.
The move came amid mounting expectation that Osaka would have a prominent role to play in Friday's opening ceremony, meaning she would have little time to rest between taking part in that event and playing Zheng.
Osaka abandoned her French Open campaign after one match, having been warned she risked expulsion for refusing to take part in news conferences during the tournament.
The reigning US Open and Australian Open champion, who has spoken of struggling with anxiety and depression, then elected to skip Wimbledon.
Each of the three grand slam events to have taken place this year has been held with fans in attendance, with Centre Court seeing capacity crowds for each of the singles finals at Wimbledon. The US Open, which begins on August 30, will allow 100 per cent fan capacity at Flushing Meadows for the final major of 2021.
However, Cash does not believe the lack of spectators at the Games will have too much of an impact on the players who have elected to travel to Japan.
"Well it's unfortunate that the Olympics won't have any fans. I think that's a real disappointment," Cash told Stats Perform.
"But 95 per cent of our life is played on an empty practice court and stadiums.
"Certainly, when you're coming through, nobody's watching you. It's only when you get to Wimbledon or something that you play with crowds, and they can make a difference. We've also been playing most of the year without them.
"To go back [to no fans] it's unfortunate, but it's not something unusual for the players. The crowd certainly does make a difference. It makes a difference with attention and with the crowd roaring and whistling or whatever they want to do."
World number two Naomi Osaka, who will return to action having withdrawn from the French Open to protect her well-being and subsequently skipped Wimbledon, is one athlete who could have benefited from the home support in Japan.
Though he is unsure of how boisterous the home crowd would have been in Tokyo, Cash still feels for the 23-year-old four-time Grand Slam winner.
"With no crowds there that's disappointing for her," he added.
"But you know, it's sort of something we've become used to on the tour - playing with empty crowds and the nerves still kick in, it is all about winning, and players tend to learn to block the crowds out quite well.
"They stay in their own world when they're on the tennis court. The urgency and the intensity of a match is not really going to change that much because the players really want this for themselves."
The world number two had seen top-ranked Ash Barty bounced out in the first round, and the face of Japan's Games looked primed for a run deep into the tournament.
But the prospects of home glory in women's tennis were dashed in round three when Osaka crumbled 6-1 6-4 to Marketa Vondrousova of the Czech Republic.
Osaka, who lit the Olympic cauldron in Friday's opening ceremony, was left scrambling for answers as to why she underperformed.
"How disappointed am I? I mean, I'm disappointed in every loss, but I feel like this one sucks more than the others," she said.
"I definitely feel like there was a lot of pressure for this. I think it's maybe because I haven't played in the Olympics before and for the first year [it] was a bit much."
Asked what went wrong against the world number 42, Osaka said: "Everything – if you watch the match then you would probably see. I feel like there's a lot of things that I counted on that I couldn't rely on today."
There were certainly mitigating circumstances that the 23-year-old might have pointed to, given she had not played since the French Open before heading into the Olympics.
Osaka pulled out of Roland Garros after winning through her first-round match, citing anxiety and pointing to episodes of depression as she explained why she refused to take part in news conferences during the tournament.
Her declarations in Paris came after the four grand slam tournaments warned she could be thrown out of their events if she persistently refused to talk to the media.
Already a four-time grand slam winner, Osaka has found plenty of public support and there was criticism of the tennis authorities for their stance.
To many in Japan, she can do little wrong, although she could also do little right against Vondrousova. Osaka had 32 unforced errors to just 10 from Vondrousova, who also hit more winners.
After saving two match points, Osaka swung a backhand wide on a third to seal her exit.
Despite her disappointment, Osaka felt she had given a reasonable account following a recent absence from the tour, which saw her miss Wimbledon.
But the Games called for more than that, and it was a deflated Osaka who spoke afterwards, explaining how the pressure on her shoulders proved overbearing.
"I've taken long breaks before and I've managed to do well," she said. "I'm not saying that I did bad right now, but I do know that my expectations were a lot higher.
"I feel like my attitude wasn't that great because I don't really know how to cope with that pressure, so that's the best that I could have done in this situation."
With Ash Barty having suffered a shock exit a day prior, Osaka is now the favourite for glory on home court and with Aryna Sabalenka and Iga Swiatek among the round-two casualties that status is sure to only be enhanced.
There was better news for Elina Svitolina and Karolina Pliskova at the Ariake Tennis Park, though, in a women's draw stacked with top-tier talent.
OSAKA NOT GETTING AHEAD OF HERSELF
Back after a self-imposed two-month hiatus, defending US and Australian champion Osaka has not missed a beat and was too good for Viktorija Golubic in a 6-3 6-2 victory.
Osaka won 24 of 26 service points in the first set and 37 of 45 in the second, facing break point only once in a one-sided affair.
"It would mean a lot to win gold here, but I know it's a process," she said. "I know these are the best players in the world and honestly I haven't played in a while, so I'm trying to take it one notch at a time.
"All in all, I'm just really happy to be here. I haven't been in Tokyo for a couple of years."
Svitolina was not as comfortable with the fourth seed rebounding from losing the opening set to defeat Ajla Tomljanovic 4-6 6-3 6-4. Maria Sakkari (14) awaits in the next round.
Carla Suarez Navarro earned her first win since recovering from cancer in round one and battled valiantly against Karolina Pliskova (5) before eventually losing in three sets.
Garbine Muguruza (7), Barbora Krejcikova (8) and Belinda Bencic all coasted through in straight sets, as did Anastasia Pavlyuchenkova (13) and Elena Rybakina (15).
TEARS FOR IGA
Swiatek, whose father was an Olympic rower, would have had strong designs on a deep run at the Games but was beaten 6-3 7-6 (7-4) by Paula Badosa.
The Pole was left in tears after the defeat, and was still sobbing at her chair several minutes after the end of the match.
Sabalenka also bit the dust, going down in three sets to Donna Vekic, while Petra Kvitova lost the deciding set of her tie with Alison Van Uytvanck 6-0 to bow out with a whimper.
Uncertainty and confusion surrounding the Games has sadly reigned for the past year due to the coronavirus pandemic.
And yet, here we are in the month the action is set to begin and the show looks certain to go on.
No international spectators will be in attendance, but limited numbers of domestic fans are due to be allowed to watch the action.
So, who are the biggest names representing Japan the locals will hope to inspire to glory? Stats Perform has taken a look…
NAOMI OSAKA
There is no other place to begin than with one of the biggest names in the whole of sport, let alone tennis right now. Naomi Osaka is a superstar with a huge global following, particularly in Japan and America. Only 23 and with four grand slams to her name, there is seemingly no limit to the level she can reach. Osaka is the defending US and Australian Open champion, but withdrew after the first round of the French Open and opted not to play at Wimbledon after revealing a long-endured battle with depression. The issue came to the fore when Osaka had announced she would not take part in media conferences in Paris to protect her mental health, starting a wider conversation over how athletes are treated.
HIDEKI MATSUYAMA
So often a nearly man, 2021 has already been a breakthrough year for the gifted Hideki Matsuyama. There were seven top-10 finishes in major tournaments before finally the 29-year-old took top billing to win the Masters at Augusta back in April. In doing so he became the first Japanese man to win a major tournament (Hinako Shibuno and Chako Higuchi have both won majors in the women's game). Olympic gold is certainly not out of the question for one of the most gifted players in golf.
KIYUNA RYO
Karate is making its Olympics debut and so is one of its greatest ever competitors in the form of Kiyuna Ryo. In 2019, Ryo won every competition he entered - including a third Asian championship - while the pandemic denied him a shot at a record fourth straight WKF world championship in June 2020. It will take a huge effort to stop Ryo, who will be 31 by the time the Games begin, standing atop the podium.
UTA ABE
The younger sibling of two-time world champion Hifumi Abe – himself off to Tokyo 2020 – judoka Uta Abe represents a serious medal hope for Japan. A two-time world champion herself in the -52kg category, she will aim to become an Olympic champion on July 25 – the same day her brother will aim to wear gold in the men's -66kg category. There is no shortage of judo talent in Japan, with Shohei Ono aiming to defend the -73kg gold he won at Rio 2016.
KENTO MOMOTA
The past 18 months have been challenging for everyone but especially for Kento Momota. In January 2020, the badminton star was involved in a road accident that claimed the life of his driver, while he required surgery on his eye socket. A combination of the injury, the global pandemic and a positive test for coronavirus kept Momota off the court for 14 months. But the two-time world champion – who won an astounding 11 titles as recently as 2019 – will be desperate to complete a fairytale ending with gold in Tokyo.
DAIYA SETO
One of Japan's greatest hopes in the pool, Daiya Seto already has an Olympic medal in the form of a bronze from Rio four years ago in the 400 metre individual medley. With four gold medals in long course world championships and as many at the Asian Games, there are plenty of high hopes for Seto.