Naomi Osaka admitted it was "a bit funny" to be deemed an essential worker as the Australian Open goes on.

The year's first grand slam is set to continue without fans from Saturday as Victoria heads into a five-day lockdown amid coronavirus concerns.

Professional athletes have been deemed "essential workers", meaning the Australian Open can continue.

Osaka, who raced into the fourth round with a 6-3 6-2 victory over Ons Jabeur on Friday, said that seemed strange.

Asked how she felt about being described as an essential worker, the Japanese star told a news conference: "Well, I'm not really sure.

"That kind of seems a bit funny. But I don't know, I don't make the rules. I'm just here just trying to have fun."

Three-time grand slam champion Osaka will face Garbine Muguruza in a blockbuster fourth-round clash.

Serena Williams labelled Victoria's five-day lockdown "rough" as the Australian Open prepares to go behind closed doors amid the coronavirus pandemic.

Fans will not be allowed to attend Melbourne Park - where crowds have been capped at 30,000 per day - from 11:59pm (local time) on Friday until Wednesday after the Victorian government announced a new state-wide lockdown to control an outbreak of the UK COVID-19 strain.

Victorian premier Daniel Andrews made the announcement as Williams booked her spot in the fourth round of the Australian Open, where the 23-time grand slam champion overcame Anastasia Potapova 7-6 (7-5) 6-2.

"I didn't know at all until the match was over. I think it's good that I didn't know," seven-time Australian Open champion Williams told reporters when asked about the lockdown.

"It's rough. It's going to be a rough few days for I think everyone. But we'll hopefully get through it."

American superstar Williams added: "It's not ideal. It's been really fun to have the crowd back, especially here. It's been really cool.

"But, you know what, at the end of the day we have to do what's best. Hopefully it will be all right."

Williams - stuck on 23 majors since winning the 2017 Australian Open in pursuit of Margaret Court's all-time record of 24 - was pushed to the limit by Russian teenager Potapova but prevailed on Rod Laver Arena.

The 39-year-old Williams - who has played and won more matches than any other woman in the tournament's history - celebrated her 90th Australian Open victory in her 101st contest.

"It was good to get through that match," said former world number one Williams as seventh seed Aryna Sabalenka awaits in the last 16. "The first set was extremely tight. I was a little tight, but it worked out. Was able to play a little more free in the second set."

The Australian Open will continue without supporters after Victoria announced a five-day lockdown amid the coronavirus pandemic. 

This year's delayed Australian Open had started on Monday with a limited amount of fans - capped at 30,000 per day at Melbourne Park - due to COVID-19 restrictions.

The Victorian government announced a new lockdown on Friday to control an outbreak of the UK coronavirus strain, state premier Daniel Andrews said.

Victoria's new state-wide restrictions will be introduced from 11.59pm on Friday - with reigning men's champion Novak Djokovic still scheduled to close out the day - until Wednesday.

"Any number of other large and small professional sport events, they will function essentially as a workplace," Andrews told reporters. "But they will not function as an entertainment event, because there will be no crowds.

"And the workforce will be the minimum that is needed in order for that to be COVID-safe and safe in lots of other contexts."

In response, the Australian Open released a statement while tournament director Craig Tiley insisted the slam will continue.

"Tennis Australia continues to work with the government to ensure the health and safety of everyone," the Australian Open said in a statement.

"The Victorian government has announced a five day lockdown commencing at 11:59pm on Friday. Australian Open sessions today and tonight will continue as planned with COVIDSafe protocols in place.

"We are notifying ticketholders, players and staff that there will be no fans onsite at the AO for five days, commencing from Saturday 13 February.

"Full refunds will be available for anyone who has tickets for these sessions and they will be advised on how to apply as soon as possible.  

"The AO broadcast-only contingency plan will commence from Saturday 13 February until restrictions are lifted. Play will continue uninterrupted on the broadcast, albeit without spectators onsite."

The Australian Open was due to get underway in January, but the COVID-19 crisis forced the year's first slam to be pushed back until February.

The lead-in tournaments across the ATP and WTA Tours took place behind closed doors in Melbourne.

Serena Williams remains on track to claim a record-equalling 24th grand slam title after overcoming Anastasia Potapova in a hard-fought battle en route to the Australian Open last 16. 

Williams - stuck on 23 majors since winning the 2017 Australian Open in pursuit of Margaret Court's all-time record - was pushed to the limit by Russian teenager Potapova but prevailed 7-6 (7-5) 6-2 in Melbourne on Friday.

Next up for seven-time Australian Open winner Williams is seventh seed Aryna Sabalenka.

Williams - who has played and won more matches than any other woman in the tournament's history - had only lost four times at a slam to a player ranked outside the top 50 and twice to players outside the top 100.

But she was challenged by Potapova in an error-riddled and difficult opening set on Rod Laver Arena, where the unheralded Russian took the match to her superstar opponent.

Williams hit 22 unforced errors to just 12 winners, faced 11 break points as she was broken twice, and saved a pair of set points en route to a tense tie-break.

Maintaining her challenge, Potapova led 4-2 and 5-3 in the tie-break, but Williams was up to the task - closing out the set in 61 minutes.

Potapova, who only broke the American's serve on one occasion in last year's opening-round loss at Melbourne Park, was not deflated following the tie-break and broke Williams in the first game of the second set.

But like the first set, Potapova was unable to hold serve and Williams took full advantage - breaking twice to secure a 16th fourth-round berth in Melbourne.

Data Slam: Williams rolls on in Melbourne
In her 101st Australian Open match, Williams secured her 90th career victory in Melbourne. The 39-year-old also improved her overall slam record to 360-51 - Martina Navratilova (306-49) is the only other player to pass 300 wins in the Open Era.
 

WINNERS/UNFORCED ERRORS
Williams – 19/31
Potapova – 18/28

ACES/DOUBLE FAULTS
Williams – 9/4
Potapova – 2/8

BREAK POINTS WON
Williams – 5/8
Potapova – 3/12

Ash Barty and partner Jennifer Brady withdrew from their doubles clash at the Australian Open amid fitness concerns over the world number one.

Barty is in the spotlight after her thigh was heavily strapped during Thursday's 6-1 7-6 (9-7) victory over fellow Australian Daria Gavrilova in the women's singles.

Australian star and 2019 French Open champion Barty was scheduled to team up with Brady for Friday's doubles contest against Elise Mertens and Aryna Sabalenka, but the duo pulled out in Melbourne.

Barty did play down the severity of the thigh issue after defeating Gavrilova, with 29th seed Ekaterina Alexandrova awaiting in the third round at Melbourne Park.

"The bandage is very big, but that's more just support so that the tape itself doesn't fall off. It's not a very subtle tape job, you often see it on a lot of the girls," Barty told a news conference on Thursday.

"The guys can hide it beneath their shorts a little bit better. Just a little bit of support. I played a lot of matches in the last 10 days after not playing for 12 months, which is natural.  It's more of an assistance than anything else."

Barty added: "It came on early Tuesday, warming up for the match. But, yeah, obviously it's not affecting the way that I can play in any way.

"It's just more giving the leg some assistance to make sure it doesn't get to a point where it's going to affect me."

Last year, Barty became the first Australian woman to reach the Australian Open semi-finals since Wendy Turnbull in 1984.

The most recent finalist from the home nation was Turnbull in 1980, while Chris O'Neil was the last champion in 1978.

Rafael Nadal said he felt pity for the woman who hurled abuse at him and flipped a middle-finger gesture before being thrown out of Rod Laver Arena at the Australian Open.

In the last match of the day on the main show court, the fan was ejected near the end of the second set, viciously taking issue with the time Nadal was taking before each serve.

She yelled out as Nadal repeatedly bounced the ball, readying himself to send down a serve to second-round opponent Michael Mmoh.

The fan appeared to call Nadal an "OCD f***", and he responded with bafflement and some amusement before looking up to the stands, with the spectator staring down at him, the middle finger on her right hand raised in an aggressive manner.

The umpire then spoke out to declare: "Thanks madam, you're delaying everything."

Moments later, security arrived to escort the woman out of the show court, to the roaring approval of the vast majority of the crowd.

"Yeah, it was to me I think," Nadal said of the gesture.

"Maybe she took too much gin or tequila. I don't know. But honestly it was a strange situation, but funny at the same time."

He had laughed at the bizarre nature of the incident when it happened, with the 20-time grand slam champion having been unused to facing any such sniping during his career.

"For me it was funny," Nadal added in his post-match news conference after tying up a 6-1 6-4 6-2 win.

"Honestly, somebody doing the finger to me. I don't know the reason, but yeah, I was surprised, but at the same time I was thinking, 'Poor girl'. Because probably she was drunk or something like this. I don't know."

Nadal will face Cameron Norrie in round three.

Rafael Nadal was able to ease through to the third round of the Australian Open on Thursday, thanks in part to the help of YouTube.

The Spaniard looked in impressive form as he swept aside Michael Mmoh 6-1 6-4 6-2 in the evening session at Melbourne Park, with perhaps the biggest hinderance for Nadal caused by a rowdy spectator who was eventually escorted out of Rod Laver Arena.

Having come through qualifying, Mmoh had rallied to stun Viktor Troicki in the opening round. However, he never threatened a stunning upset of the 2009 champion, who will next face Cameron Norrie.

Meanwhile, Daniil Medvedev marked his birthday with a routine win of his own, the in-form Russian stretching his unbeaten run to 16 matches to suggest he is a serious contender for the title.

Stefanos Tsitsipas found life a little tougher in his outing but while the Greek survived the scare to move on in the main draw, fellow seeds Borna Coric and Lorenzo Sonego were knocked out.

NO VIDEO NASTY FOR NADAL

Ever the consummate professional, Nadal revealed he did his research online to find out more about second-round foe Mmoh, who had to get through three qualifying rounds just to make the main draw.

The world number 177 managed more aces than the 2009 champion but failed to create a break-point opportunity in a contest that lasted one hour and 47 minutes. Like the fan who disturbed play by shouting and making gestures towards Nadal as he served for the second set, Mmoh perhaps knew he was heading for the exit.

"I always have a lot of respect for every opponent. Yesterday, I was watching some videos of him on YouTube, trying to know a little bit more about him," Nadal said in his on-court interview after the match.

"Every day when you go onto the court, anything can happen - you can win, you can lose. You need to be ready to accept both things."

Norrie is next for the 34-year-old, the Briton defeating qualifier Roman Safiullin in four sets.

NO TIME TO CELEBRATE FOR MEDVEDEV

While Roberto Carballes Baena offered some resistance in the second set, Medvedev provided a further demonstration of his obvious talent with a 6-2 7-5 6-1 thrashing of the Spaniard.

The fourth seed from Russia was on court for one hour and 44 minutes but insisted afterwards his focus will now switch to his next opponent - Filip Krajinovic - rather than celebrating turning 25.

"There's no time to celebrate my birthday in a tournament. I got presents from my wife, but I'll soon look to my next match," he said. "If I'd have lost, I probably would go and celebrate, but I won so I can't now."

Krajinovic defeated Pablo Andujar 6-2 5-7 6-1 6-4 to progress. He was triumphant in the only previous meeting with Medvedev on the ATP Tour, winning in straight sets when they went up against each other at Indian Wells in 2019.

TSITSIPAS FIGHTS LIKE LION, LOPEZ EXTENDS SLAM STREAK

Tsitsipas was stretched to the limit but came out on top against Thanasi Kokkinakis 6-7 (5-7) 6-4 6-1 6-7 (5-7) 6-4 in a gruelling encounter.

Tsitsipas - who reached his maiden grand slam semi-final at the Australian Open two years ago - rallied from a set down to eventually see off Kokkinakis after four hours and 32 minutes.

Local hope Kokkinakis was playing his first major since the 2019 US Open and threatened a huge upset against the fifth seed.

"Great match towards the very end, and I fought like a lion," said Tsitsipas, who next meets Mikael Ymer. "I fought like a real warrior out there, and it was an amazing ending with lots of emotion and great spirits."

In his 75th consecutive grand slam, 39-year-old Feliciano Lopez came from two sets down to top 31st seed Sonego 5-7 3-6 6-3 7-5 6-4.

Fabio Fognini was involved in a thrilling five-setter against Salvatore Caruso, which ended with the pair engaging in a tense verbal exchange that led to security intervening.

Record-chasing Rafael Nadal cruised through to the third round of the Australian Open after outclassing Michael Mmoh in straight sets.

Nadal is bidding to move clear of Roger Federer with a record 21st grand slam title, while the world number two is also looking to become the first man in the Open Era to win each of the four majors twice.

The 2009 Australian Open champion remains on track thanks to Thursday's 6-1 6-4 6-2 victory in warm conditions under the Rod Laver Arena lights.

Nadal was aiming to maintain his perfect record against qualifiers at the Australian Open - the Spanish star having won 25 of the 26 matches played against qualifiers at a grand slam, with his only defeat coming to Dustin Brown at Wimbledon in 2015.

He did not have much trouble against Mmoh, Nadal schooling the 23-year-old in a merciless and devastating first set, which saw him win 80 per cent of first serves, hit 10 winners and break twice.

Mmoh, who was looking to surpass the achievement of his father after Tony reached the Australian Open second round in 1988, provided some flashes of quality.

On just one occasion had Nadal lost to a player as low as number 177 Mmoh at ATP Tour-level - world number 690 Joachim Johansson in 2006, while Nick Kyrgios (144) was the lowest-ranked player to upstage the veteran at a slam via Wimbledon in 2014.

But it was trademark Nadal, who despite Mmoh's best efforts, broke in the fifth game for a 3-2 lead and never looked back, though one unruly fan tried their best to derail the former world number one before being escorted out of the stadium.

Amid concerns over his back pre-tournament, Nadal raced through the third set with a couple of highlight shots to set up a clash against Cameron Norrie.

Data Slam: Nadal stays perfect

Nadal improved to 50-0 when winning the opening two sets at the Australian Open, dating back to 2004.

WINNERS/UNFORCED ERRORS
Nadal – 40/24
Mmoh – 16/25

ACES/DOUBLE FAULTS
Nadal – 7/3
Mmoh – 8/4

BREAK POINTS WON
Nadal – 5/11
Mmoh – 0/0

Sofia Kenin's title defence came to a shock end in the second round of the Australian Open, where world number one Ash Barty advanced amid injury concerns.

Kenin was looking to become the first woman to defend her crown at Melbourne Park since Victoria Azarenka in 2013, instead, she was a high-profile casualty in warm conditions on Thursday.

Barty, who lost to Kenin in last year's semi-finals in Melbourne, stayed alive with a straight-sets win over fellow Australian Daria Gavrilova.

Former world number one Karolina Pliskova also progressed beyond the second round as fifth seed Elina Svitolina blitzed American sensation Coco Gauff.

KENIN OUSTED IN BOILOVER

The American star arrived at the year's first grand slam with high expectations and looking to become the first woman to go back-to-back at a major since Serena Williams in 2016.

But fourth seed Kenin fell to experienced Estonian Kaia Kanepi 6-3 6-2, having tallied 10 winners and 22 unforced errors in windy conditions in Melbourne - the scene of her breakthrough slam more than 12 months ago.

It was Kenin's first defeat to a player ranked outside the top 50 since going down to then-number 54 Iga Swiatek in the 2020 French Open final.

Asked why she was nervous pre-match, Kenin told reporters: "It's like the outside pressure. I felt really nervous. I haven't felt my game for, I don't know how long, but I haven't really felt my game so well, even in my first round. 

"I played well, but still haven't felt 100 per cent game-wise. It's obviously tough."

STRAPPED THIGH? NO WORRIES FOR BARTY​

Barty's left thigh was heavily strapped amid concerns but the 2019 French Open champion still booked her spot in the third round with a 6-1 7-6 (9-7) win over countrywoman Gavrilova.

The first Australian woman to reach the semi-finals in Melbourne since 1984, following last year's run, Barty gave up a 5-2 lead in the second set before saving two set points in the tie-break.

Reflecting on Kenin's surprise exit, Barty talked up the standard of the WTA Tour.

"There are no easy matches," said Barty, who next meets 29th seed Ekaterina Alexandrova for a spot in the round of 16. "There are no easy matches in any tour event, any slam, anything. I think every time you walk on the court, you have to try and be able to bring your best tennis to be able to compete with everyone. 

"That's just the level that there is now on the women's side. That's something really exciting about women's tennis now, is that every single match, it's a fair match. You go out there, you play hard, you try to do the best that you can."

PLISKOVA AVENGES LOSS, SVITOLINA TOO GOOD FOR GAUFF

Beaten by Danielle Collins in the third round of the Yarra Valley Classic just eight days ago, sixth seed Pliskova got the better of the 2019 Australian Open semi-finalist this time around.

Pliskova - also a semi-finalist at Melbourne Park two years ago - defeated Collins 7-5 6-2 and next plays 25th seed Karolina Muchova.

"I just played better in some moments, which I didn't last week. Then she was not playing that well as she did last week," Czech star Pliskova said. "I knew if I at least maintain little bit, just play at least similar as I was playing last week, I knew it's going to be difficult for her to repeat what she played last week. I think she really played great."

Owning a 6-1 record in the second round at Melbourne Park - falling only at this stage in 2016 - Svitolina produced a mature performance to conquer 16-year-old star Gauff 6-4 6-3 on centre court as 26th seed Yulia Putintseva awaits. 

Elsewhere, seeds Belinda Bencic, Elise Mertens, Anett Kontaveit, Jennifer Brady and Donna Vekic moved through.

Nick Kyrgios has the weapons to overcome the "super physical" Dominic Thiem at the Australian Open on Friday.

The eccentric Australian continued to excite at Melbourne Park with a five-set win over Ugo Humbert in the second round, saving two match points.

Kyrgios, 25, is into the third round of a grand slam for the 15th time in his career, but it has been a difficult hurdle for him to cross. He is 6-8 in the third round of majors, although three of those wins – and just one loss – have come at the Australian Open.

While he has all the weapons, Kyrgios faces third seed Thiem, the US Open champion and last year's runner-up in Melbourne.

"He's probably one of the most physical guys on tour. He's an extremely good player. I have actually seen him progress. He's a bit older than I am. I actually saw him in juniors and then I saw him struggle for a couple years, futures, challies, and then to see him get to the top of the game. It's been actually pretty cool to see him develop and finally find what he needs to do to win matches," Kyrgios said about Thiem after overcoming Humbert.

"He trains like an absolute animal. He's consistent every day. And I actually have a lot of respect for him. I think his style of tennis is not easy to play. He's super physical, but I'm not even thinking about it. Like, I'm just hurting thinking about playing him right now."

He added: "Whatever happens against Thiem happens. I'm going to go out there, serve, play with instinct, and if it's enough, it's enough. If it isn't, I'm all right with that."

With much of the talk at the year's first major focused on the fast courts, Kyrgios' serve will be vital.

The Australian has seen 50 per cent of his first serves in the opening two rounds go unreturned, with 44 aces. He has also served at 72 per cent and won 81 per cent of the points when his first serve has gone in.

Thiem has recorded wins over Mikhail Kukushkin and Dominik Koepfer to begin the tournament, winning 13 of 27 return games. Kyrgios has won eight of 42 return games.

Kyrgios has been among the men more willing to serve and volley to begin the event, playing 26 such points and winning 16. He has also won 39 of 55 net points, while Thiem is an impressive 31 of 36.

Novak Djokovic is among those who have talked about the fast courts at Melbourne Park this year, and the world number one said that would suit the big servers. Thiem said he had never played on courts as fast at a grand slam so far in his career.

"I prefer last year's courts, if I could choose. It's pretty fast, as I said the days before. It's probably one of the fastest grand slam tournaments I've played so far," he said. "Well, we have to get used to it, yes. But if I have to choose, I would choose the last year's condition."

The opportunity is there for the big-hitting Kyrgios, but he will need to be at his best.

A teary Sofia Kenin admitted she was unable to handle the pressure of defending her Australian Open title after a second-round exit.

The American fourth seed departed at Melbourne Park on Thursday, when she was beaten by Kaia Kanepi 6-3 6-2.

Victoria Azarenka was the last woman to defend the Australian Open crown in 2013, while Serena Williams was the most recent to go back-to-back at any major, winning Wimbledon in 2015 and 2016.

Kenin, 22, said she struggled to cope with the pressure of defending a grand slam title for the first time.

"Obviously I haven't experienced that. I obviously felt like I'm not there 100 per cent physically, mentally, my game. Everything just feels real off obviously. It's not good," she told a news conference.

"I know I couldn't really handle the pressure. I'm not obviously used to this, so right now I just got to figure out how to play at that level that I played at.

"Because like today and those matches, it just hasn't been there. It's weird. I've been practising for two weeks. Luckily I've been able to practice. I felt fine in practice. Just couldn't do that in the game."

Kenin had 22 unforced errors against Kanepi, while she failed to convert any of her seven break points.

After a second loss in as many meetings with Kanepi, Kenin gave credit to the 35-year-old Estonian.

"She obviously played well. I obviously felt like I couldn't find my rhythm.  I was obviously way too nervous," she said.

"Yeah, I mean, she played really well. She came up with some good shots. She obviously had a good plan against me. I just couldn't execute my shots."

Ash Barty insisted her leg issue was not impacting her at all after reaching the Australian Open third round.

The world number one overcame Australian compatriot Daria Gavrilova 6-1 7-6 (9-7) on a warm and windy Rod Laver Arena on Thursday.

But Barty's left thigh was heavily strapped and she gave up a 5-2 lead in the second set before saving two set points in the tie-break.

However, the 2019 French Open champion played down the severity of the issue.

"The bandage is very big, but that's more just support so that the tape itself doesn't fall off. It's not a very subtle tape job, you often see it on a lot of the girls," Barty told a news conference.

"The guys can hide it beneath their shorts a little bit better. Just a little bit of support. I played a lot of matches in the last 10 days after not playing for 12 months, which is natural.  It's more of an assistance than anything else."

Barty added: "It came on early Tuesday, warming up for the match. But, yeah, obviously it's not affecting the way that I can play in any way.

"It's just more giving the leg some assistance to make sure it doesn't get to a point where it's going to affect me."

Barty will face Ekaterina Alexandrova in the third round.

Sofia Kenin's Australian Open title defence came to an end with a second-round loss to Kaia Kanepi on Thursday.

Kenin, who won her first and only grand slam title in Melbourne last year, fell to Kanepi 6-3 6-2 on a warm and windy day.

The American fourth seed had lost her only previous meeting against Kanepi and was again no match for the 35-year-old Estonian.

Kenin's second-round loss marked her earliest exit at a grand slam since Wimbledon in 2019.

She finished with 10 winners and 22 unforced errors, while Kanepi was far steadier with 22 and 17 respectively.

It continued a tough run for defending champions in Melbourne, where Victoria Azarenka was the last woman to go back-to-back in 2012 and 2013.

The last woman to defend any major crown was Serena Williams at Wimbledon in 2016.

Kanepi moved into the third round of a major for the first time since the 2019 French Open.

She will next face Croatian 28th seed Donna Vekic.

Novak Djokovic admitted there was plenty of room for improvement after coming through a "difficult spot" at the Australian Open, where Nick Kyrgios thrilled the crowd with an impressive comeback.

Top seed Djokovic was made to work for his 6-3 6-7 (7-3) 7-6 (7-2) 6-3 triumph against Frances Tiafoe as he reached the third round in Melbourne. 

Kyrgios is also through, albeit he even surprised himself by rallying from the brink of defeat to knock out 29th seed Ugo Humbert in the evening session. 

Stan Wawrinka was on the wrong of an upset on Wednesday, but there were no such problems for fellow seeds Dominic Thiem, Alexander Zverev, Diego Schwartzman and Milos Raonic. 

Meanwhile, Denis Shapovalov and Felix Auger-Aliassime will have to put their friendship to one side when they face each other next, the former setting up the all-Canadian clash by beating Bernard Tomic in three sets.

'PASSIVE' DJOKOVIC STILL MAKING PROGRESS

In the first meeting between the pair, the impressive Tiafoe went toe-to-toe with Djokovic on Rod Laver Arena.  

The 23-year-old American's performance – coupled with the Melbourne heat – made the eight-time Australian Open champion sweat, albeit Djokovic felt he could have made life easier for himself.

"I was at times not feeling my timing as well as I normally am. Credit to him. I think he has managed to come out with a great performance and quality of tennis. He put me in a difficult spot," he said. 

"I had my chances early in the second set. If I broke him there, maybe the course of the match would be different.   

"But again, he was holding his serve very well. I was not really using my break-point chances very well. At times I was too passive. Just wasn't feeling the ball today as well as I normally do." 

Next up for Djokovic is another player from the United States in the form of Taylor Fritz, who ousted compatriot Reilly Opelka in a five-set battle.

IN THE NICK OF TIME

Kyrgios described his clash with Humbert as "one of the craziest matches I've ever played" after prevailing 5-7 6-4 3-6 7-6 (7-2) 6-4 - much to the delight of an enthralled audience who watched the drama unfold on John Cain Arena.

The Australian smashed a racket, lost his cool with umpire Marijana Veljovic over a faulty net cord sensor and had to save a pair of match points before eventually coming out on top in a see-saw battle.

"I just remember, down that end, when I was a couple of match points down, I don't know what was going on," Kyrgios - who dropped to his knees after sealing victory - said in his on-court interview.

"If you were inside my head, there were some dark thoughts in there. But I live to fight another day and hopefully I can continue to play good tennis in front of you guys."

His reward is a clash with Thiem, the third seed having dismissed the challenge of German Dominik Koepfer in straight sets as he dropped just six games.

STAN-D AND DELIVER

Wawrinka appeared on course to survive a serious scare when he rallied from two sets down against Marton Fucsovics, but the Swiss was unable to seize on the chances that came his way in a tense tie-break. 

Fucsovics had needed over four hours to overcome wild card Marc Polmans in the previous round and, once again, found a way to get over the finishing line at the end of a Melbourne marathon. 

The Hungarian trailed 6-1 during the decisive breaker, yet hit back to stun the 17th seed 7-5 6-1 4-6 2-6 7-6 (11-9). For Wawrinka, there was frustration at the missed opportunities, albeit he also praised his conqueror. 
  
"From 6-1 up, I started to hesitate a little bit in the way I was playing," he said. "I wanted to put the ball maybe too much in and I [was] not going completely for my shots and that's when I started to miss a little bit and it helped him to come back in the match.  

"He was fighting well, he's a tough player, he's a good player and he deserved to win." 

Serena Williams and Naomi Osaka sizzled in the scorching Melbourne heat on day three of the Australian Open. 

Williams, aiming once more for a record-equalling 24th singles grand slam, made serene progress from round two on what was the hottest day of the tournament so far. 

It was a similar story for Osaka, who is aiming to become a two-time champion at Melbourne Park, but Simona Halep had to dig deep while Bianca Andreescu and Petra Kvitova were early casualties on Wednesday.

PLAIN SAILING FOR SERENA AND OSAKA

Williams' perfect start to the season extended to 5-0 as she swatted aside Nina Stojanovic 6-3 6-0 to set up a round-three meeting with Anastasia Potapova – the same opponent she overcame in Melbourne in the first round a year ago. 

The seven-time Australian Open champion is looking forward to renewing acquaintances with the Russian. 

"It's always a fun, interesting match [against Potapova]. I'm gonna go home, get ready and just do the best," she said.  

"We're all out here to have fun and I'm happy to be out here, and just to be playing in front of crowd again is really cool. So every day is just fun." 

Osaka, the current US Open champion and the winner in Melbourne two years ago, hammered former world number four Caroline Garcia 6-2 6-3 on Rod Laver Arena in the evening session. 

The Japanese star is set to face her friend Ons Jabeur for the first time in an official match in round three. 

"She's really funny," Osaka said of her next opponent. "I don't know if you guys watch any of her interviews. I think she is really funny and nice.  

"I think the match I am going to play against her will be really difficult, but I'm looking forward to it." 

HALEP SURVIVES TOMLJANOVIC TEST

In contrast to Williams and Osaka's comfortable wins, second seed Halep was taken to the brink by home favourite Ajla Tomljanovic, who won the first set and was serving for the match in the third. 

However, 2018 finalist Halep broke back when trailing 5-4 in the decider and battled through with a 4-6 6-4 7-5 victory in a match that saw a combined 94 unforced errors (57 for Tomljanovic, 37 for Halep). 

"I was expecting that she would play very hard and very strong. I expected it to be a difficult match, but it was more than I thought. But I'm really happy that I can smile now," Halep said.  

"I was not that positive when I was talking to myself. I didn't talk about the score, I was just blaming myself, that I'm not strong enough to win against her. But in the end mentally I was maybe a bit stronger than her, and I didn't want to give up." 

Last year's losing finalist Garbine Muguruza (14) was too good for Ludmilla Samsonova in a 6-3 6-1 win, while French Open champion Iga Swiatek (15) dispatched Camila Giorgi 6-2 6-4. 

Aryna Sabalenka (7), Marketa Vondrousova (19) and Veronika Kudermetova (32) all made it through, but fellow seed Elena Rybakina (17) was beaten in straight sets by Fiona Ferro.

EARLY EXITS FOR ANDREESCU AND KVITOVA

Andreescu became the latest scalp for veteran Hsieh Su-Wei, who earned a commanding 6-3 6-2 victory and is now 4-3 against top-10 players in the slams since 2017. 

Eighth seed Andreescu won the US Open in 2019 but missed the entirety of last year with a knee injury, while her preparation here was disrupted by spending 14 days in quarantine after her coach tested positive for coronavirus. 

"After my first round, I thought I would feel more exhausted, but I felt amazing. Also, today the weather was a bit tricky. Being in the heart of quarantine I could have had those extra two weeks of like being in the heat and getting used to sweating and all of that," she said. 

Next up for Hsieh is Sara Errani, who defeated Venus Williams 6-1 6-0. The veteran American rolled her ankle towards the end of the first set and, despite needing two medical timeouts, valiantly saw out the match. 

Kvitova was a runner-up to Osaka in 2019 and appeared on course to recovery after dominating the second set against Sorana Cirstea. 

But amid sweltering conditions, the Czech ninth seed went on to lose the decider. 

"It was quite a rollercoaster, for sure," she said. "Unfortunately I couldn't take the chances to win the first set.  

"I think that was really the key of the match. She really had a great day today; she played a good game. I didn't really bring the best tennis today. It's really hurting."