World number 26 Madison Keys was one of three seeded players to be eliminated in the second round of the Silicon Valley Classic in San Jose on Wednesday.

The American third seed was beaten by China's Zhang Shuai 7-5 7-6 (7-5) in one hour and 39 minutes.

Keys sent down 7-1 aces but Zhang, ranked 51st in the world, was excellent on return, converting four of her 11 break points.

Fourth seed Daria Kasatkina was also in danger after losing the first set but rallied to win 3-6 7-5 6-3 over France's Caroline Garcia.

"It was a tough match. From my point of view, I think the level of the game was very good, and I'm really happy that I was able to turn the match in the second set," Kasatkina said in the on-court interview.

Ninth seed Alison Riske was emphatically beaten by Croatian Ana Konjuh 6-1 6-4 in one hour and 13 minutes, while sixth seed Petra Martic bowed out to Poland's Magda Linette 7-5 7-6 (7-5).

Danielle Collins eased past Shelby Rogers 6-4 6-3 to book her spot in the second round at the Silicon Valley Classic on Tuesday.

World number 36 Collins proved too strong for American compatriot Rogers, winning in one hour and 25 minutes.

Collins will meet another American in the second round, with Sloane Stephens up next.

Former U.S. Open winner Stephens beat Caty McNally 6-4 6-2 earlier in the day.

Yulia Putintseva, meanwhile, eased her way into the second round with a 7-5 6-3 win over Croatian Donna Vekic.

Putintseva will face Australian Ajla Tomljanovic in the second round after she fought back to overcome Amanda Anisimova 1-6 7-5 7-5.

France's Kristina Mladenovic won 6-4 6-4 over Han Na-Lae, while American Claire Liu won in three sets against Dayana Yastremska.

Mladenovic will face top seed Elise Mertens, while Liu meets second seed Elena Rybakina.

Ninth seed Alison Riske defeated former top 10 player CoCo Vanderweghe in the opening round of the Silicon Valley Classic in straight sets on Monday.

Riske, who made the Wimbledon quarter-finals in 2019 and is currently ranked 37th in the world, won 6-3 6-4 in one hour and 28 minutes.

In a match which saw eight breaks converted, Riske's ability to win on her first serve proved the difference.

Vanderweghe, who made the Silicon Valley Classic finals in 2012 and 2017, was broken five times and won 58.1 per cent of first serve points.

Croatian sixth seed Petra Martic eased into the second round with a 6-3 6-3 victory over Anastasija Sevastova.

Martic will face Magda Linette next, after the Pole accounted for Dutch qualifier Lesley Kerkhove 6-3 6-3.

Ana Konjuh defeated Marie Bouzkova in a three-set epic which last two hours and 41 minutes, winning 7-5 3-6 7-5.

China's Zhang Shuai won over Emma Raducanu in straight sets, along with Carolina Garcia who defeated Emina Bektas.

Alexander Zverev followed up his stunning win over Novak Djokovic by storming to Olympic gold in the men's singles final.

A thumping 6-3 6-1 victory against Russian Olympic Committee's Karen Khachanov was the perfect way for world number five Zverev to land the biggest title of his career.

He won 10 of the last 11 games of his semi-final against world number one Djokovic and carried that form into Sunday's title match, brushing aside the threat across the net.

It makes him Germany's first men's singles champion at the Olympics. Steffi Graf won the women's title as part of a calendar Golden Slam in 1988, and four years later Boris Becker and Michael Stich teamed up to take doubles gold.

For the man who won the ATP Finals in 2018 and reached last year's US Open title match, this marked a step forward in a career many expect will eventually feature grand slam titles.

He secured a swift break in the first set against Khachanov, who was outstanding in the semi-finals against Pablo Carreno Busta but could not impose his game in the gold-medal match.

Another break followed and the set was gone in 43 minutes.

The second set rushed by in a mere 36 minutes, with Zverev against striking early and never looking back.

He created two break points in the second game of that set, and although Khachanov saved them, a third soon followed and the Russian netted on the forehand.

The momentum was all one way and there was never a moment when Khachanov, ranked 25th by the ATP, looked as though he might pose some danger. 

Zverev gave himself a first match point when he punched away a backhand volley, and the glory belonged to the German when Khachanov slapped a forehand into the net on the next point.

BENCIC DENIED GOLDEN DOUBLE

Belinda Bencic was the surprise champion in the women's singles and the Swiss had a chance to land a second gold medal on Sunday when she and Swiss partner Viktorija Golubic lined up in the doubles final.

It was not to be for Bencic and Golubic, however, as they were soundly beaten by the prolific Czech pair of Barbora Krejcikova and Katerina Siniakova.

A 7-5 6-1 win for the reigning French Open champions meant Bencic and Golubic were left with the silver medal.

But there was little in the way of regret for the Swiss pair, with Bencic showing off both her gold and silver medals after the match, saying: "We are overjoyed. We will fly back on Monday with other medallists. It's a great feeling to know people are waiting and they acknowledge the medals we won for our country.

"The week here was incredibly beautiful. We experienced so many emotions, and it's great to go back and share all of these emotions with everyone at home.

"It's not just about the medals or the titles, it's about the memories you create that will last forever. To share this with Viki is unbelievable.

"The whole week I never felt like I was in a normal tournament or playing alone. She was alongside me the entire way. I always tell her we won this gold medal together as well. When we will be 80 years old and have a coffee, we will talk about this moment and I cannot wait for that."

Ash Barty has conceded her dramatic Olympics mixed doubles defeat will be tough to take.

The world number one saw her hopes of winning a gold medal for Australia at Tokyo 2020 brought to an end on Friday.

Barty and partner John Peers won the first set against Russian Olympic Committee duo Andrey Rublev and Anastasia Pavlyuchenkova.

But Rublev and Pavlyuchenkova turned it around to win an epic clash 5-7 6-4 13-11 and reach the final.

With Barty already eliminated in the singles and women's doubles competitions, the best she can now hope for is a bronze medal alongside Peers.

They will meet Serbia's Novak Djokovic and Nina Stojanovic for the last spot on the podium.

"It is a tough one to swallow," said Barty. "I think those tie-breaks at times, they go either way and we just didn't quite have the run of the grain. 

"We put ourselves in a position to win the match, we just weren't able to close it out. It was a good level, no doubt disappointing."

Another chance at a medal means Wimbledon champion Barty will try to get over her loss swiftly.

She added: "But we get to fight for a medal - this one hurts but we still have an opportunity to play another match and try to win a medal for Australia. 

"We pick ourselves up pretty quickly, move on and know that we will give it our all and keep fighting right until the end.

"It's been quite a while since we've had an Australian medallist here [in tennis] at the Olympics so we're looking forward to that challenge."

In the men's doubles, Nikola Mektic and Mate Pavic are Olympic champions after they beat fellow Croatia representatives Marin Cilic and Ivan Dodig in the final.

Marketa Vondrousova landed another huge scalp in the form of Elina Svitolina to book her place in the gold medal match at Tokyo 2020 against Belinda Bencic.

It has been a memorable week for Vondrousova, who knocked out cauldron-lighter and "face of the games" Naomi Osaka in round three.

One more hurdle still stands in her way in the form of ninth seed Bencic, who fought hard for a three-set triumph over Elena Rybakina.

VONDROUSOVA MARVELS AGAIN

Vondrousova has had a Games to remember and she was a 6-3 6-1 winner against heavily fancied fourth seed Svitolina, becoming the first female Czech to reach an Olympic singles final in the process.

It means the Czech Republic will have a women's singles competitor on the podium for the second straight Games after Petra Kvitova finished with bronze at Rio 2016.

Incredibly, Vondrousova did not even automatically qualify for these Games with Karolina Pliskova, Barbora Krejcikova, Kvitova and Karolina Muchova ahead of her in the qualifying pecking order.

Vondrousova opted to use her protected ranking, dating back to a wrist injury prior to the pandemic, meaning Muchova missed out. Though criticised at the time, she is the last of the four remaining.

TEARS FOR BENCIC

Switzerland has a proud history of tennis stars but neither the legendary Roger Federer nor the great Martina Hingis have won Olympic gold in a singles event. Bencic has the chance to do that, though.

She had to go the distance against Rybakina in a 7-6 (7-2) 4-6 6-3 victory, with Bencic fighting back from 5-2 down in the first set.

Eventually Bencic came through in two hours and 44 minutes and the tears poured as she made the final.

"My emotions right now... it's too high," Bencic told the ITF website. "To have a medal, it's the greatest thing. Even to be here as an athlete, in the Olympics, it's amazing."

It means Switzerland will medal for the fourth straight Games with Federer, Stan Wawrinka, Hingis and the recently retired Timea Bacsinszky all having medalled.

The last Swiss gold medallist was at Barcelona 1992 where Marc Rosset won the men's singles.

Elsewhere, singles world number one Ash Barty remains in the hunt for mixed doubles gold. She and partner John Peers defeated Greek pair Stefanos Tsitsipas and Maria Sakkari – winning on a 10-point tie-break after the first two sets were shared.

Paula Badosa was forced to withdraw from her quarter-final against Marketa Vondrousova and taken from the court on a wheelchair after suffering from heatstroke at Tokyo 2020.

Tuesday saw heavy downpours in the Japanese capital, but the hot and humid conditions from earlier in the week returned early on Wednesday with temperatures at times going above 30 degrees Celsius.

Vondrousova, who had shocked home favourite Naomi Osaka in the previous round, won the first set 6-3 at Ariake Tennis Park but her opponent was clearly struggling as she prepared to play the second set.

She required medical assistance to depart the court, as Vondrousova progressed to the final four.

VONDROUSOVA COMMENTS ON THE HEAT

The conditions for the tennis in Tokyo have been a quite literal hot topic with both Daniil Medvedev and Novak Djokovic stating matches should start at 3pm so the majority can be played as temperatures cool.

Vondrousova explained how it was playing in the searing heat, saying: "It was a big struggle from the beginning.

"I warmed up in the morning and I felt it was really hot and humid. Also, I was a bit tired from yesterday because I had doubles too.

"But I knew she had too [singles and doubles]. I felt like we both were struggling from the beginning.

"I was just thinking, you have to stay there mentally, just fight for every point and just see what happens. It's good for me that I can have some rest now.

"It's all about the head too. You have to stay there mentally and fight. Even when you lose the point, you have to get up and fight again. It's really a struggle here with the weather, but that's it, we have to fight."

OLYMPICS LIKE A SLAM FOR SVITOLINA

Next up for Vondrousova is a last-four meeting with Elina Svitolina, the fourth seed and highest-ranked player left in the women's draw.

The Ukrainian was a 6-4 6-4 victor over Camila Giorgi and talked up the significance of winning Olympic gold.

"I know that for Ukraine, [the Olympics] is a really big thing," Svitolina said. 

"I value the Olympics as a grand slam, and I tried to prepare to bring my best tennis. Here I am in the semi-final, and I can get a chance to get a medal. It's very special for me, but I try to take one match at a time."

Belinda Bencic (9) came through 6-0 3-6 6-3 against Anastasia Pavlyuchenkova on the other side of the draw. She will face Elena Rybakina (15), who was too good for seventh seed Garbine Muguruza in a 7-5 6-1 win.

Ash Barty was beaten along with partner Storm Sanders in the women's doubles quarter-finals earlier on Wednesday but the world number one bounced back to win her first-round mixed doubles match with partner John Peers.

The Australian duo beat Argentina's Horacio Zeballos and Nadia Podoroska 6-1 7-6 (7-3).

Naomi Osaka was never preordained to win gold at the Tokyo Olympics but it had felt that way until she ran into Marketa Vondrousova.

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."

Naomi Osaka saw her Tokyo 2020 gold medal hopes go up in smoke after a painful defeat and admitted: "This one sucks more than the others."

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."

Naomi Osaka is taking things "one notch at a time" at Tokyo 2020 after another convincing performance in round two on Monday.

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.

Maryna Zanevska fought back from a double-break down in both sets of the Poland Open final to claim her first WTA Tour title at the expense of Kristina Kucova.

Zanevska twice found herself trailing 3-0 in the battle between two first-time WTA singles finalists, but rallied to win 6-4 7-6 (7-4) on the clay in Gydnia on Sunday.

World number 165 Zanevska had never played in a quarter-final on the main tour before making the last four in Lausanne last week and the in-form Belgian now has a first title to her name.

The 27-year-old was granted a special-exempt entry into the Gdynia main draw due to her run in Switzerland and is now projected to re-enter the top 120 in the rankings.

Kucova was left to reflect on what might have been, having started both sets so strongly before failing to press home her advantage in a topsy-turvy championship match.

The Czech, ranked 150th, saved four match points before forcing a tie-break but was beaten in an hour and 51 minutes.

Naomi Osaka is feeling "a little bit refreshed and happy again" after returning to tennis with a convincing 6-1 6-4 triumph over Zheng Saisai in her Tokyo 2020 opener.

The four-time grand slam winner has not featured since the first round of the French Open two months ago where she abandoned her campaign following a warning she risked expulsion over her refusal to take part in news conferences during the tournament.

Osaka, who is the reigning US and Australian Open champion, then decided to skip Wimbledon after opening up on her battles with anxiety and depression.

The 23-year-old was granted the honour of lighting the flame for Tokyo 2020 on Friday and two days later made a successful return at the Ariake Tennis Park, where she represents one of Japan's greatest medal hopes for the Games.

"I feel like, more than anything, I'm just focused on playing tennis. This, playing the Olympics, has been a dream of mine since I was a kid, so I feel like the break I took was very needed," she said.

"But I feel definitely a little bit refreshed and happy again.

"I felt really nervous being in Japan and playing here for the first time in maybe two years, and for it to be my first Olympics. 

"It was definitely really nerve-wracking. But I am glad I was able to win, she is a very tough opponent.

"It's been a while since I played but I feel, more than anything, just happy to be out here. We are playing in a pandemic, and it is really tough for everyone."

Asked how she felt to be talking to the press again, she said: "For me, honestly I don't feel that weird about it.

"It might feel weird to you guys, but I don't know. I'm happy that I guess you guys are asking me questions but more than anything I was just focused on playing tennis and I guess I feel a little bit out of my body right now."

Osaka then revealed that her starring role in Friday's opening ceremony came about in March.

"I was super honoured," she said. That’s a position you dream about and not anyone can do it so when they asked me if I wanted to I was very surprised but very honoured and I'm just happy to be here and happy to play, especially in Tokyo."

The playing conditions have been a quite literal hot topic over the first two days, with the sweltering heats causing issues for players.

Daniil Medvedev and Novak Djokovic were among those to speak out about the decision not to play matches later in the day Tokyo, where temperatures have regularly been above 30 degrees.

Osaka, though, has no such issues, adding: "It feels fine for me. I have played a couple of tournaments here, of course they resurfaced it since I was last here, but I love being here, and I actually really like the weather."

Ash Barty's chances of winning singles gold at Tokyo 2020 came to a juddering halt at the first hurdle as she suffered a shock 6-4 6-3 to Spain's Sara Sorribes Tormo.

The world number one and recently crowned Wimbledon champion was among the favourites for glory in the women's event but put in an uncharacteristically error strewn display at the Ariake Tennis Park.

In total, the amiable Australian racked up a whopping 55 errors in a match that lasted a little over an hour and a half.

Sorribes Tormo had never faced off against Barty before but kept cool amid the stifling Tokyo conditions to progress to a second-round tie with Fiona Ferro of France.

It also marked the first time the 24-year-old had ever beaten a player ranked number one in the world.

Barty's Tokyo adventure is not over just yet, though. On Saturday she and childhood friend Storm Sanders made it through round one of the women's doubles with a 6-1 6-2 beating of Japanese Nao Hibino and Makoto Ninomiya.

Naomi Osaka lighting the Olympic cauldron will have helped increase the exposure for the sport of tennis around the world, according to Novak Djokovic.

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."

Iga Swiatek says adjusting to the tricky Tokyo conditions will be key to winning gold after she came through her Olympics opener on Saturday.

The Polish athlete was the highest-ranked seed in action in the women's singles in the Japanese capital and comfortably dispatched of Mona Barthel 6-2 6-2.

World number one Ash Barty gets her individual campaign underway on Sunday but the Wimbledon champion was a doubles victor on the first day of action on the tennis courts.

SWIATEK OUT TO ADJUST

Swiatek was on court for a little over an hour, breaking serve six times and firing down 13 winners to Barthel's eight.

The tough hot and humid conditions were a big talking point at Ariake Tennis Centre on Saturday, and Swiatek – whose father represented Poland as a rower at the 1988 Olympics – had her say.

"I'm pretty happy that I'm into the second round and for sure not only the temperature was hard, but also the sun because on one side it was pretty hard to serve," she said. 

"But we had to adjust quickly and change our toss, so that was hard, but you know I would say the players who can adjust quicker are going to be the best ones here."

KREJCIKOVA BENEFITS FROM DIYAS RETIREMENT

Eighth seed Barbora Krejcikova was 5-2 up against Zarina Diyas before her opponent had to withdraw with an ankle problem.

The Czech now meets Leylah Annie Fernandez in the second round. Fellow seeds Belinda Bencic (9), Anastasia Pavlyuchenkova (13), Maria Sakkari (14) and Elena Rybakina (15) all made it through round one.

But Kiki Bertens, the 16th seed, was sent packing 6-4 3-6 6-4 by Marketa Vondrousova.

BARTY REVELS IN TEAMING UP WITH CHILDHOOD FRIEND

Barty is fresh off her triumph at SW19 earlier this month, and the amiable Aussie started her Olympics adventure alongside long-time friend Storm Sanders.

The sixth feeds hammered home pair Nao Hibino and Makoto Ninomiya 6-1 6-2.

"Playing with my childhood friend in what is a dream for both of us is really cool. And to be here in some of the most unique circumstances I think ever for an Olympic Games, it's really awesome for us," Barty said.

"We're very grateful and thankful that we're able to be here to play and to experience what is really cool Games."