The Tokyo Olympics are now in full swing and there are another 22 gold medal events to come on an action-packed Tuesday at the Games.

Plenty of focus will be on the Tokyo Aquatics Centre once again, where four medals are on the line, while the women's triathlon will also take centre stage.

Simone Biles, Naomi Osaka and Katie Ledecky are just some of the superstar names that will be in action on the fourth full day of the 2020 Games.

Stats Perform picks out of some of the standout action to look out for.

CAN BILES PUT BLUNDERS BEHIND HER?

Biles struggled to find top gear in her Games entrance on Sunday, albeit making it through to each of her finals, and there is no room for any slip-ups in the women's team final.

The Russian Olympic Committee finished above the United States at a major event for the first time since 2010 in qualifying, setting up an intriguing battle in the final.

The pressure is on Suni Lee, Jordan Chiles, Grace McCallum and indeed Biles, the latter of whom is aiming to add to the four golds won in Rio five years ago.

USA-JAPAN MEET IN SOFTBALL FINAL

Team USA's women's softball team recovered from behind to beat Japan 2-1 in their final round-robin game and finish top of the standings.

Japan finished second and the two sides are therefore set to face off in a huge gold medal match at Yokohama Baseball Stadium.

Mexico and Canada meet in the bronze medal contest earlier on Tuesday in a tasty warm-up match for the main event.

LEDECKY AND TITMUS RESUME RIVALRY

After winning four golds in Rio five years ago, Ledecky had the chance to add four more to her collection in Tokyo.

She fell short in the first of those events, however, with Australia's Ariarne Titmus taking gold in Monday's gripping 400m freestyle final.

While a medal is not on the line on Tuesday, Ledecky will be eager to lay down a faster time than her rival in the 200m freestyle heats ahead of Wednesday's showpiece.

OSAKA GOES AGAIN

Face of the Games Okaka followed up lighting the Olympic cauldron on Friday with victories over Zheng Saisai and Viktorija Golubic in her first two matches in the tournament.

The four-time grand slam winner has a quick turnaround in matches as world number 41 Marketa Vondrousova awaits in the third round on Tuesday.

Fellow home favourite Kei Nishikori is also in action in the men's event, with Marcos Giron standing between him and the last 16.

WOMEN'S TRIATHLON TOUGH TO CALL

There was drama before the men's triathlon had even officially got underway on Monday, with an inflatable boat carrying photographers causing a false start.

Norway's Kristian Blummenfelt won the competition and now it is over to the women, with 54 athletes in contention to claim gold.

The field is wide open this time around, though the likes of Katie Zaferes and Georgia Taylor-Brown, of Team USA and Great Britain respectively, will have their eyes on the top prize.

Norway's Kristian Blummenfelt said he never had a doubt he would win the triathlon, and his confidence never wavered as he pulled away late to take the gold. 

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. 

The third full day of the Tokyo Olympics sees 21 gold medals up for grabs during a packed programme.

Plenty of eyes will be on the Tokyo Aquatics Centre, where four swimming golds will be on the line, while the first women's skateboarding champion will be crowned.

The rugby sevens event gets under way and the men's triathlon will also take place.

Stats Perform picks out some of the standout action.

LEDECKY STEPS UP GOLD QUEST

After winning four golds in Rio five years ago, Katie Ledecky has the chance to add four more to her collection in Tokyo, starting with the women's 400m freestyle.

The United States competitor set a world record time in the event in 2016, but she will face a big challenge from Australia's Ariarne Titmus this time.

Titmus was marginally faster than Ledecky in the heats, though whether that edge will count for anything on the day remains to be seen.

WILL IT BE ANOTHER PEATY BLINDER?

Great Britain's Adam Peaty is nothing short of a phenomenon in the world of swimming and will be looking to retain his 100m breaststroke title.

Peaty qualified for the final in a dominant manner, his time of 57.56s just two hundredths of a second off his own world record pace.

Arno Kamminga of the Netherlands is expected to be Peaty's biggest threat, having produced a personal best of 57.80s in the previous heat.

MORE SEVENS HEAVEN FOR FIJI?

Fiji's triumph in the men's rugby sevens was one of the more remarkable stories of the Rio Games and the islanders will now be out to retain their title in Tokyo over the coming weeks.

They begin their group campaign on Monday with games against tournament hosts Japan and then Canada later in the day.

MEN'S TRIATHLON WIDE OPEN

The men's triathlon is a tough one to call, with back-to-back champion Alistair Brownlee not taking part in this year's event.

The likes of Alex Yee, Kristian Blummenfelt, Morgan Pearson and Tyler Mislawchuk are among those to watch in one the standout events at any Games.

BILES SURVIVES, NOW MEN MUST THRIVE

After Simone Biles struggled to find top gear in her Games entrance on Sunday, albeit making it through to each of her finals, Monday's gymnastics event is the men's team final.

Japan are the defending champions and led the way in qualifying, but they are expected to face stiff competition from China and the Russian Olympic Committee team. Watch out for Russian maestro Nikita Nagornyy and Japan's Daiki Hashimoto among a star-studded cast.

OSAKA BACK IN ACTION

It is proving to be a busy Games for Naomi Osaka, who followed lighting the Olympic cauldron on Friday with a first-round tennis win on Sunday.

Japan's four-time grand slam winner is back on court on Monday, looking to inch closer to the women's singles final. Awaiting her is Swiss world number 50 Viktorija Golubic, and it will be their first match encounter. Men's title hopefuls Novak Djokovic and Daniil Medvedev are among those also due in action.

WOMEN'S SKATEBOARDING MAKES ITS DEBUT

Japan's Yuto Horigome made history on Sunday by winning the first Olympic gold in men's skateboarding. On Monday, it is the turn of the women.

Among those competing in the event are Kokona Hiraki of Japan and Team GB's Sky Brown, who are aged 12 and 13 respectively.

After plenty of falls and drama in the men's equivalent, expect more of the same in this inaugural event.