Ash Barty may have her focus on winning the Australian Open right now but suggested a career change could be on the cards in the future.  

The world number one made sure she will still be competing during the second week of the tournament in Melbourne by beating Ekaterina Alexandrova in straight sets.  

But, having played international cricket for Australia before switching to tennis, could the multi-talented Barty be considering trying another sport?  

Elsewhere in Saturday's action, Karolina Pliskova lost her cool – and also a couple of rackets – as she slipped to defeat against the impressive Karolina Muchova in an empty Rod Laver Arena, with fans not able to be present due to a five-day lockdown in the state of Victoria.

Elina Svitolina had no such problems in her third-round match, while Elise Mertens was victorious in just over an hour against Belinda Bencic. Jennifer Brady ended Slovenian qualifier Kaja Juvan's run in the first grand slam of the year.

AUSSIE RULES, OK? 

After winning 6-2 6-4 without ever needing to be at her peak, Barty was cheekily asked by former doubles partner Casey Dellacqua – now working in the media – whether she may be set to switch paths again, once her tennis career has come to an end.  

Australian rules football was the answer – but Dellacqua maybe got more than she bargained for from her former playing partner during the on-court interview. 

"I thought it was our deal, we're going to AFLW. It's ABCD [the nickname for the pairing from their doubles career]. We come as a package, and I know we will be going to the [Richmond] Tigers that is for sure," Barty said. "You can't go to Carlton. You have to come to the 'Tiges' with me."

Dellacqua replied: "I need to get out there and start practicing some kicking, but you are good. I would love to do that one day." 

For Barty, though, the next challenge facing her is Shelby Rogers, who knocked out 21st seed Anett Kontaveit during the evening session.  

MAKING A RACKET 

A disgruntled Pliskova was not impressed when punished for smashing up a racket during her match with compatriot Muchova. 

Having received a warning when throwing a racket to the floor during the course of the final game in the opening set, the sixth seed then vented her frustration again on another while in the players' tunnel.  

An official witnessed the incident and reported it to chair umpire Alison Hughes, who punished the Czech with a point penalty before she began serving to open the second set.  

"It's off court, I'm allowed to do what I want," Pliskova insisted when querying the decision to the official. She would go on to hold before recording two successive breaks, yet somehow failed to force a decider.  

Muchova rallied from 5-0 down in sensational fashion, winning seven games on the spin to triumph 7-5 7-5 to make it through to the last 16.

CONTRASTING PROGRESS FOR SEEDS

Svitolina has still yet to drop a set in the tournament after overcoming 26th seed Yulia Putintseva by a 6-4 6-0 scoreline.  

The fifth seed was twice down a break in the first set but, after eventually coming out on top to take a 1-0 lead, breezed through the second in a hurry.  

"She has a very different game style from what I played my last two rounds, so it wasn't easy at the beginning to adjust," Svitolina said. "As soon as I was feeling better, I just stepped my game, and it was quite a comfortable win after." 

Next up will be Jessica Pegula, who is through to the fourth round at a slam for the first time in her career after thrashing Kristina Mladenovic 6-2 6-1.  

There was also success for another American in the main draw, Brady defeating Juvan in straight sets. Her reward is a clash with Donna Vekic, the 28th seed having to save a match point before eventually seeing off Kaia Kanepi 5-7 7-6 (7-2) 6-4 after two hours and 38 minutes on court. 

Ash Barty battled back to win both sets against Ekaterina Alexandrova and book a place in the fourth round of the Australian Open. 

The world number one triumphed 6-2 6-4 after one hour and 21 minutes on court, though there was no crowd present to cheer on the home favourite due to the five-day lockdown in place in Victoria. 

Barty admitted that, with fans having been allowed into Melbourne Park earlier in the tournament, there was a different – if not completely unpleasant – atmosphere to proceedings in the evening session on Margaret Court Arena.

"It's very strange, it changes the sound of the court a little bit," the Australian – who played with her left thigh heavily strapped having pulled out of doubles duty on Friday – said during her on-court interview.

"I love the crowd, but I love the sound the ball makes. It feels a bit like practice."

Barty lost her opening service game as she quickly fell 2-0 behind at the start of the contest, though she hit back impressively to take the opener against the 29th seed.

The 2019 French Open champion claimed six successive games, hitting just five winners as the policy of keeping the ball in play paid off thanks to 16 unforced errors from her opponent. 

Alexandrova was more consistent in the second set, leading to a break of serve that she quickly consolidated to make the score 4-2. 

However, the Russian was unable to cling on to her advantage and, when serving to stay in the match, let slip two opportunities to extend proceedings. Barty will next face Shelby Rogers, who knocked out 21st seed Anett Kontaveit in straight sets.

Elina Svitolina said playing behind closed doors at the Australian Open felt "a bit disturbing" after having fans in attendance earlier in the week.

The Ukrainian fifth seed booked her spot in the fourth round in Melbourne with a 6-4 6-0 victory over Yulia Putintseva on Saturday.

But no fans were in attendance on Margaret Court Arena as Victoria started a five-day lockdown due to coronavirus.

Svitolina, who will face Jessica Pegula in the last 16, said she felt the difference.

"It was very different conditions. I played a night match at 7:00 with a good crowd. Now it was completely different. It was for sure a bit disturbing, I would say, in some ways sad," she told a news conference.

"But it is what it is. I had to accept. I had to have a good mindset, not thinking too much about that. I just tried to focus on my game."

Svitolina reached the fourth round in Melbourne for the third time in four years after mixing 18 winners with 20 unforced errors.

But the 26-year-old said the lack of fans meant the third-round encounter felt like a practice match.

"It feels like that. I actually had few thoughts about it today. It feels like this. I tried to convince myself that it's a grand slam and that we are playing an important match. I have to focus on my match," Svitolina said.

"But for sure there's some thoughts and there is I say some low moments that can sneak into the mind. It's what we have to deal with. I'm trying my best to do it."

Naomi Osaka and Garbine Muguruza set up a blockbuster clash at the Australian Open, while Aryna Sabalenka cannot wait to face Serena Williams.

As Williams was tested before winning through, Osaka and Muguruza raced through their third-round outings in Melbourne on Friday.

Osaka and Muguruza dropped just seven games between them to set up what will be their first meeting, which will take place without fans in attendance as Victoria prepares to move into a five-day lockdown beginning on Saturday due to coronavirus concerns.

Sabalenka also progressed and will next face Williams, while Simona Halep cruised through.

OSAKA, MUGURUZA STORM THROUGH

Osaka, the three-time grand slam champion, brushed past fellow seed Ons Jabeur 6-3 6-2 in the third round.

The Japanese star, winner of the Australian Open in 2019, is looking forward to facing fellow major champion Muguruza.

"I've practised with her once, but it was on grass, and I was younger. It was maybe like a couple years ago," Osaka said.

"But I just remember being really impressed by her, and for me, I've watched her win Wimbledon and win the French Open when I was younger, and I've always wanted to have the chance to play her. So for me, this is really exciting."

A finalist at the Yarra Valley Classic last week, Muguruza's strong start to the Australian Open continued with a 6-1 6-1 thrashing of Zarina Diyas.

"I don't think we've played each other before. Just looking forward for a fourth round, a good fourth round, playing the top players," Muguruza – who has lost just 10 games in the first three rounds – said ahead of facing Osaka. "I feel like that's always the right way, you know, a good sign. Just expecting a good match."

JOB DONE FOR SERENA

Williams' bid for a record-equalling 24th grand slam singles title remains on track after overcoming Russian teenager Anastasia Potapova 7-6 (7-5) 6-2.

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.

Next up for Williams is Sabalenka, who was too good for Ann Li, winning 6-3 6-1 to reach a major fourth round for just the second time in her career and first in Melbourne.

The Belarusian seventh seed is not daunted by the task facing her when she meets the American for the first time.

"I want to get this thrill. Can I say thrill? I said it right. So it's going to be a thrill. But, yeah. I'm going to do everything I can," Sabalenka said.

HALEP THROUGH AS SEEDS CRUISE

Halep reached the fourth round in Melbourne for the sixth time with a convincing 6-1 6-3 win over Russian 32nd seed Veronika Kudermetova.

Awaiting the two-time major winner in the fourth round is Iga Swiatek after the Polish 15th seed got past Fiona Ferro 6-4 6-3.

Swiatek thrashed Halep 6-1 6-2 on her way to the French Open title last year.

Marketa Vondrousova, the 2019 French Open runner-up, reached the fourth round of the Australian Open for the first time after beating Sorana Cirstea 6-2 6-4.

Up next for the Czech 19th seed is Hsieh Su-wei, who battled past Sara Errani 6-4 2-6 7-5 after two hours and 44 minutes.

Errani had won her previous three meetings with Hsieh in straight sets, including winning a set 6-0 - known as a 'bagel' in tennis parlance - in each of those victories.

It meant Hsieh, 35, had a simple plan against the Italian.

"I don't remember when I lose to someone but someone reminded me I eat the bagel every time so I said, 'Okay, I will try to not take any bagel today'," she said.

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.

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.

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.

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."

Serena Williams is embracing the absence of line judges at this year's Australian Open as the record-chasing American superstar dubbed herself a "futurist, like Iron Man" after reaching the third round. 

The Australian Open is taking place without linespeople as a response to coronavirus restrictions at Melbourne Park, where "Hawk-Eye Live" technology is being used on every court. 

It is the first grand slam to replace all line judges with technology as the tournament seeks to limit the number of people on court amid the COVID-19 pandemic.

After easing past Nina Stojanovic 6-3 6-0 on Wednesday, 23-time grand slam champion and seven-time Australian Open winner Williams welcomed the use of technology.

"I like it," Williams, who is looking to equal Margaret Court's record of 24 slams, told reporters when asked about the technology post-match. "I didn't like it in Cincinnati because they had that in Cincinnati and I was, it was different. It was weird. 

"I like it now because it takes away a lot of the human error, which clearly I definitely don't need. I should be the biggest fan of that. 

"But I feel like sometimes I definitely still want to see that ball, but I'm like, okay, even if I see it, the computer's going to show me what the computer just said. So that's kind of how I think about it. 

"I'm a futurist, like Iron Man, so I definitely love technology and it's something that I invest in and so, yeah, I really think is right up my alley."

Williams owns a 359-51 grand slam record in her illustrious career – the only other player to pass 300 victories in the Open Era is Martina Navratilova (306-49).

The 39-year-old Williams is bidding to win her 11th major crown since turning 30.

Only Court (three), Navratilova (three), Chris Evert (two), Billie Jean King (two), Ann Jones (one), Angelique Kerber (one), Li Na (one), Flavia Pennetta (one) and Virginia Wade (one) have won grand slam silverware in their 30s.