Simona Halep revealed her Rome withdrawal this week was caused by a torn calf muscle, a blow that casts doubt on her prospects of playing the French Open.

Former world number one Halep had to be helped off court by coach Darren Cahill after she was injured while leading Angelique Kerber 6-1 3-3 in the second round of the Internazionali d'Italia on Wednesday.

The two-time grand slam champion on Friday announced the extent of her injury. Her misfortune comes with just over two weeks remaining until the clay-court grand slam at Roland Garros gets under way on May 30.

Wimbledon is the next major on the calendar after the Paris slam, with the All England Club tournament scheduled to start on June 28 in London.

"After an MRI here in Rome I can confirm that I have small tear high up in the left calf," Romanian Halep posted on her social media accounts.

"I will fly home today and begin recovery in the pool and gym on Monday.

"I'm staying positive and will do everything i can to speed up my return."

Halep, now 29 years old, won her first major title in Paris three years ago and went on to be crowned Wimbledon champion in 2019.

Simona Halep suffered a worrying leg injury just over two weeks out from the French Open at the Internazionali BNL d'Italia, where Serena Williams and Naomi Osaka crashed out.

Halep, the 2018 French Open champion, had dominated the first set against Angelique Kerber, winning 6-1, but came off the court with an apparent calf problem with the scores level at 3-3 in the second.

She received treatment but an emotional Halep was forced to withdraw from the clash, the defending champion handing victory to Kerber.

The Romanian was then helped from the grandstand court, leaving the area with strapping on her leg and a heavy limp, raising doubts about her ability to compete at Roland Garros, where she would likely be one of the favourites.

Earlier Williams made her first appearance on the tour since February, losing the 1,000th match of her glittering career to Nadia Podoroska, who reached the semi-finals in Paris last year.

Podoroska prevailed 7-6 (8-6) 7-5, with 23-time grand slam champion Williams not too downhearted by a defeat to an accomplished clay-court player.

"It's tough to have a first match on clay. It was definitely kind of good to go the distance and to try to be out there, but clearly I can do legions better," Williams said. 

"She has a good game, for sure, obviously. She's very consistent. Overall, it was good for me to play such a clay-court player on clay today, but it's a little frustrating. But it's all right. It is what it is.

"I have been training for months, but it feels definitely different on clay to make that last adjustment. Just filling out the game, finding the rhythm. Even sliding and confidence with that, with movement. That's always like a little struggle in the first two matches, and then I'm raring to go."

Osaka has yet to find her footing on clay and the reigning Australian Open champion came up short in the second round as she suffered a surprise loss to Jessica Pegula.

Pegula said after her 7-6 (7-2) 6-2 win: "I know she doesn't love clay, so I just tried to be the clay court player out there today, and it worked just good enough."

World number one Ashleigh Barty had no such difficulties in her 6-4 6-1 over Yaroslava Shvedova, but fourth seed Sofia Kenin was a shock loser to Barbora Krejcikova.

Petra Kvitova was beaten in three sets by Vera Zvonareva but Madrid champion Aryna Sabalenka, last year's French Open champion Iga Swiatek, Elina Svitolina, Karolina Pliskova and Garbine Muguruza all progressed while teenager Coco Gauff knocked out 17th seed Maria Sakkari.

Elise Mertens twice came back from the brink to beat Simona Halep and reach a Madrid Open quarter-final against former doubles partner Aryna Sabalenka.

Third seed Halep was the highest-ranked player in action on Wednesday but came unstuck against Mertens despite taking the opener and leading by a break in each of the subsequent sets.

Mertens emerged a 4-6 7-5 7-5 winner after two hours and 34 minutes, defeating Halep for the first time on clay and only the second time on any surface.

There were opportunities for both players throughout and Halep struck first, losing her break lead in the first but recovering on this occasion.

The Romanian, a two-time winner who has also twice lost in the final in Madrid, twice cancelled out a deficit in the second but could not then capitalise on a lead of her own.

Mertens battled back and broke to love to level the match, then maintained her composure to see out a back-and-forth decider once Halep had again forged ahead.

"She played really well, and she definitely deserved to win because she was stronger in the end," Halep said.

"I cannot say I played bad, but I did some mistakes, important mistakes. Sometimes it's just a little bit and the match is going away."

Sabalenka is up next for Mertens, although she had a much more straightforward path through the third round.

Jessica Pegula held her up for only 52 minutes in a dominant 6-1 6-2 success.

In the same half of the draw, Anastasia Pavlyuchenkova upset another seed, following up her straight-sets victory over Karolina Pliskova by beating Jennifer Brady in three. She plays Karolina Muchova next.

At L'Open 35 de Saint-Melo, second seed Rebecca Peterson came from behind to see off Xiyu Wang, while Tamara Zidansek and Arantxa Rus also produced comebacks.

Nina Stojanovic survived three sets, but Christina McHale crashed out to Viktoriya Tomova.

Naomi Osaka suffered a shock second-round exit to Karolina Muchova at the Madrid Open, but there was no such trouble for Simona Halep as she held off Zheng Saisai.

Second seed Osaka was playing just her second match on clay since the 2019 French Open due to injury issues and became the latest big name to fall at the hands of Muchova.

The world number 20, who had already defeated two top-five players this season, prevailed 6-4 3-6 6-1 in a time of one hour and 49 minutes in the Spanish capital.

Osaka has now lost two of her last three matches, having been eliminated from the Miami Open quarter-finals by Maria Sakkari at the end of March.

"I think today for me it was quite different from the last time I lost in Miami, and I actually think I played much better here, so I'm very happy about that," Osaka said.

"I think what I can take away from this is that I tried my best throughout the entire match. I think tennis-wise, I felt I was too defensive in the first set.

"I wouldn't say I’m happy that I lost, but I think I learned a lot. So that's all I can hope for."

Two-time champion Halep has yet to drop a set in this year's tournament after seeing off unseeded opponent Zheng 6-0 6-4.

Halep took nine games in a row at the start of the match but, like in her opening-round win over Sara Sorribes Tormo, she had to hold off a late surge from her opponent to advance.

Next up for Halep is a last-16 showdown with Elise Mertens, who beat Elena Rybakina 7-6 (7-4) 7-5 in the last of Sunday's matches.

Fifth seed Aryna Sabalenka safely advanced earlier in the day thanks to a 6-3 6-3 win against Daria Kasatkina, while Sakkari beat Anett Kontaveit 6-3 6-1.

Sabalenka was on course to face Victoria Azarenka for a place in the quarter-finals, but the Belarussian withdrew from her match with Jessica Pegula because of a back injury.

Elsewhere, Jennifer Brady, who knocked out fellow American Venus Williams in the first round, eased past Jelena Ostapenko 6-2 6-1.

Brady faces a tricky test in the next round with Anastasia Pavlyuchenkova, who defeated sixth seed Karolina Pliskova 6-0 7-5, seeking another scalp.

Naomi Osaka quickly adapted to playing again on clay as she was among the seeds to triumph in Friday's action at the Madrid Open.

Osaka had not featured on the red dirt since a third-round exit at the 2019 French Open, missing out on competing on the surface last year due to injury.

This year's Australian Open champion stumbled out of the blocks against Misaki Doi, quickly falling 3-0 behind in the opener, but recovered from the early setback to prevail in straight sets.

The second seed hit 26 winners in a 7-5 6-2 triumph over her compatriot, who has now lost all three of their meetings on the WTA Tour.

"You obviously want to play well against a player that's from the same country," Osaka said.

"I never really know what to expect because I feel like she always plays better when I play against her, so it's a bit tough to manage controlling my emotions. But I think I was able to do it pretty well."

Simona Halep also won in her opener at the event, the third seed racing through the first set before holding off a fightback from Sara Sorribes Tormo in the second.

Halep – who needed 83 minutes to clinch a 6-0 7-5 victory – has been crowned champion twice in Madrid, the first time coming in 2016 before she returned a year later to successfully defend the title.

Aryna Sabalenka wasted little time in seeing off the challenge of Vera Zvonareva, the fifth seed producing 37 winners in a 6-1 6-2 win, her first ever in the event.

Maria Sakkari found the going much tougher before eventually ousting Amanda Anisimova, losing the first seven games in a row before rallying for a 0-6 6-1 6-4 triumph.

Daria Kasatkina was also pushed in her opener, with a 4-6 6-4 7-6 (7-1) win over Irina-Camelia Begu taking just over three hours.

Karolina Pliskova had to go the distance after falling a set behind against Coco Gauff, while two-time finalist Victoria Azarenka came out on top in a deciding set against Ekaterina Alexandrova.

In the final match on a busy day, Jennifer Brady won 6-2 6-4 in an all-American clash with Venus Williams.  

Ash Barty will meet Aryna Sabalenka in the Stuttgart Open final after Simona Halep's quest to win the tournament for the first time fell short.

World number three Halep had claimed straight-set wins over Ekaterina Alexandrova and Marketa Vondrousova en route to the semi-finals, but met her match in the form of Belarusian Sabalenka, who triumphed 6-3 6-2.

A nine-time singles champion, Sabalenka made it into a 14th career final without conceding a single break, as she managed to keep Romanian Halep at arm's length.

Standing between Sabalenka and a 10th singles title is world number one Barty who, on her 25th birthday, came from behind to defeat Elina Svitolina 4-6 7-6 (7-5) 6-2.

Making her tournament debut in Stuttgart, Barty had overcome Laura Siegemund and Karolina Pliskova, but found herself at 5-4 down in the second set, with Svitolina serving for the match.

The fourth seed failed to take her chance, with Barty breaking and subsequently biting back in the tie-break, before carrying the momentum into the decider to claim a third straight win over Svitolina.

Top seed Elise Mertens made it to her second Istanbul Open as she saw off her doubles partner and birthday girl Veronika Kudermetova 6-1 6-4.

It means Mertens will be playing in two finals on Sunday, as she pairs up with Kudermetova again in the doubles showdown against Nao Hibino and Makoto Ninomiya.

Mertens' win ended Charleston champion Kudermetova's nine-match winning streak, and set up a final against the unseeded Sorana Cirstea, who defeated Marta Kostyuk 6-4 6-4.

World number one Ash Barty survived a scare to reach the semi-finals of the Stuttgart Open with a 2-6 6-1 7-5 win over Karolina Pliskova.

The Australian started slowly in the quarter-final of the WTA 500 tournament on Friday as Pliskova broke her serve twice in taking the first set, before Barty hit back with three breaks of her own to force a decider.

Barty was two points away from losing on five occasions as world number nine Pliskova served for the match at 5-4 in the final set.

But she broke the Czech's resolve eventually, sealing victory when Pliskova hit the ball long after a baseline rally.

The win was Barty's eighth consecutive victory over a top-10 opponent and she said in a media conference afterwards that facing top players in the world brings the best out of her.

"When you come up against top-10 opponents, you have to go to that level above to be able to compete. They force you to bring your best," Barty said.

"With a lot of the girls in the top 10, we've had plenty of matches that have gone either way, different experiences, so each time I love that challenge of testing myself against the best."

Barty will face Elina Svitolina in the semi-finals after she saved two match points to claim a 6-7 (4-7) 7-5 6-2 victory over Petra Kvitova.

In the other half of the draw, Simona Halep breezed through to the semi-finals with a 6-1 6-4 win over Ekaterina Alexandrova.

Halep clinically closed out the first set, and although Alexandrova showed more fight in the second, the world number three did not allow her a route back into the match.

Halep will face Aryna Sabalenka following the Belarusian's 7-5 4-6 6-1 win over Anett Kontaveit.

In the Istanbul Cup, top seed Elise Mertens secured her place in the semi-finals with a 6-4 6-4 win over Katerina Siniakova.

Mertens will face Veronika Kudermetova who fought back from a set down to clinch a 2-6 6-3 6-3 win over Ana Bogdan.

The other semi-final will see Sorana Cirstea play Marta Kostyuk. Cirstea progressed after Fiona Ferro, trailing 6-4, retired through injury while Kostyuk beat Ana Konjuh 7-5 4-6 6-3.

Simona Halep started her clay-court season in style at the Stuttgart Open as she saw off Marketa Vondrousova in straight sets on Thursday.

Second seed Halep is hunting her first appearance in a Stuttgart final, and she looked in fine form as she took just 56 minutes to dismiss Vondrousova 6-1 6-3.

Vondrousova – the 2019 French Open runner up – had won both of her previous meetings with Halep, but on this occasion she was no match for the world number three, who has won every major European clay-court tournament other than Stuttgart.

"Starting the clay-court season makes me very happy and motivated, extra motivated actually," Halep said in a post-match news conference.

"I missed playing matches. I had a few weeks without an official match and it was kind of tough when I started the match, but my mind was strong enough just to give focus on what I have to play. So, I did it great and today it was a great match.

"I was a little bit nervous before the match because I played twice against her and she beat me every time.

"It is important for my mind, for my game, because the clay-court season is going to be very tough. Now this match gave me confidence that my level is high, and if I keep doing the same thing, I will be good."

Facing Halep in the quarter-finals will be Ekaterina Alexandrova, who defeated world number 12 Belinda Bencic, and joining them in the final eight is Elina Svitolina, who defeated Angelique Kerber 7-6 (7-4) 6-3.

Two-time Stuttgart champion Kerber and Svitolina had faced off 13 times before Thursday's contest, and the Ukrainian is now 9-5 up in that head-to-head tussle.

While Aryna Sabalenka also progressed, Karolina Pliskova teed up a clash with top seed Ash Barty by coming from behind to beat Jelena Ostapenko 6-7 (7-9) 6-4 6-3.

At the Istanbul Open, top seed Elise Mertens also needed three sets to forge a path into the last night.

Mertens had to show her mettle in a contest which lasted over two hours, but she eventually got the better of Viktorija Golubic 6-4 4-6 6-1.

Veronika Kudermetova also made the last eight, as did Ana Bogdan, who fended off Barbora Kreijcova, while Fiona Ferro defeated Vera Zvonareva.

World number one Ash Barty moved through to the last 16 of the Miami Open, where Simona Halep's campaign came to a premature end.

Defending champion and top seed Barty was too good for Jelena Ostapenko in Saturday's showdown between the former French Open winners.

Two-time grand slam winner Victoria Azarenka also moved through to the fourth round of the WTA Premier tournament.

Halep, however, succumbed to a shoulder injury in Miami.

CLASH OF PAST AND PRESENT NUMBER ONES

Barty and former world number one Azarenka will go head-to-head for a place in the quarter-finals.

Australian star Barty accounted for Ostapenko 6-3 6-2 as she extended her winning streak at the Miami Open to eight matches.

Barty, who tallied nine winners to 14 unforced errors, rallied from 2-0 down in the second set by reeling off six successive games to advance.

"Today felt like I was a lot sharper and switched on and ready to go from the very first point," Barty said afterwards.

Three-time Miami champion Azarenka trumped Angelique Kerber 7-5 6-2 in the third round.

Azarenka – the 14th seed – fought back from a 4-1 deficit in the opening set to get the better of the three-time major winner.

"She's a very talented player. I always have been a huge fan of her game and the way she plays, the way she handles herself. She has a lot of variety," Azarenka said on facing Barty. "She has pretty much every single shot there is. [It's] going to be a great match."

INJURED HALEP PULLS OUT

Two-time grand slam champion Halep withdrew due to a shoulder injury as Anastasija Sevastova benefited from a walkover.

"I'm very sorry to I have to pull out of the singles and doubles at the Miami Open, but my injury doesn't let me play here as expected," said Halep.

"I'm sad that I can't continue, I wanted to come here to give my best and play many matches but unfortunately I can't. 

"Hopefully next year I will come back healthy and better."

Next up for Sevastova is wildcard Ana Konjuh, who stunned 15th seed and reigning French Open champion Iga Swiatek 6-4 2-6 6-2.

SVITOLINA AND SABALENKA ROLL ON

Ukrainian fifth seed Elina Svitolina booked her spot in the round of 16 after overcoming fellow seed Ekaterina Alexandrova 7-6 (7-1) 6-4.

Two-time Wimbledon winner Petra Kvitova stands in the way of a quarter-final berth – the ninth seed was too good for 17th seed Johanna Konta 6-1 6-2.

Seventh seed Aryna Sabalenka, meanwhile, prevailed 7-6 (7-4) 6-4 against Veronika Kudermetova.

Belinda Bencic – the 11th seed – was sent packing 4-6 6-4 6-4 by Marketa Vondrousova, who will take on Sabalenka.

Simona Halep has withdrawn from the Miami Open due to a shoulder injury.

Halep beat Caroline Garcia in the second round in Florida on Thursday, but an issue with the world number three's right shoulder prevented her from facing Anastasija Sevastova.

The two-time grand slam champion said: "I'm very sorry to I have to pull out of the singles and doubles at the Miami Open, but my injury doesn't let me play here as expected.

"I'm sad that I can't continue, I wanted to come here to give my best and play many matches but unfortunately I can't. 

"Hopefully next year I will come back healthy and better."

Sevastova will face either French Open champion Iga Swiatek or Ana Konjuh in the round of 16.

Ash Barty completed a great escape to stay alive at the Miami Open, where Simona Halep also progressed.

Barty faced a match point but the defending champion and world number one dug deep to prevail in three sets against Kristina Kucova on Thursday.

Romanian third seed Halep also needed three sets at the WTA Premier tournament in Miami.

BARTY PRODUCES COMEBACK

In her first match outside of Australia in more than 12 months, Barty survived to top qualifier Kucova in Miami.

Barty trailed 5-2 in the third set, with Kucova earning a match point at 5-3 but the Australian star saved it and won the final five games of the match to secure a spot in the round of 32.

Winner of the 2019 French Open, Barty sent down an equal career-high 15 aces in two-and-a-half hours.

"Today was really hard work, and I enjoyed every single minute of it," Barty said on court post-game. "There’s nothing like coming through a test like that, and now I get another opportunity in a couple days' time to play another tough match and test myself again."

Next up for Barty is 2017 Roland Garros champion Jelena Ostapenko, who outlasted Kirsten Flipkens 6-2 5-7 6-3.

HALEP REACHES MILESTONE

Halep brought up her 400th WTA main-draw triumph with a 3-6 6-4 6-0 victory over France's Caroline Garcia.

After dropping the opening set, Halep won 11 of the final 12 games to move through to the next round.

Halep won in one hour, 48 minutes, drastically improving on her first serve after the opening set while coming to grips with Garcia's kick serve.

"I needed time to get used to it and to get the rhythm," Halep said about Garcia's serve having improved her head-to-head record to 7-1, with Anastasija Sevastova awaiting in the last 32 after eliminating American sensation Coco Gauff.

Halep received attention on her shoulder early in the second. "I struggled with my serve," Halep said. "I struggled with my shoulder a little bit, so the attention was a little bit on the pain. [After that] I started to relax myself."

KERBER'S DOUBLE BAGEL

Three-time grand slam winner Angelique Kerber has been up and down in recently, but she flexed her muscles with a 6-0 6-0 humiliation of Renata Zarazua.

Aryna Sabalenka – the seventh seed – was another one to fend off match points before rallying 0-6 6-3 7-6 (11-9) past Bulgarian qualifier Tsvetana Pironkova in a gutsy.

Last year's French Open champion Iga Swiatek knocked off Barbora Krejcikova 6-4 6-2, while ninth seed and two-time Wimbledon champion Petra Kvitova got past Aliza Cornet 6-0 6-4.

Fifth seed Elina Svitolina survived to beat Shelby Rogers 3-6 7-5 6-3 and two-time major winner Victoria Azarenka benefited from a walkover.

Sloane Stephens ended her losing run to start the year with a hard-fought three-set win over France's Oceane Dodin in the first round of the Miami Open on Wednesday.

Former US Open champion Stephens, ranked 49th in the world, defeated Dodin 6-7 (6-8) 6-4 6-2.

Stephens progresses to the second round where the top seeds, including top three Ash Barty, Naomi Osaka and Simona Halep, will be introduced and she will face 28th seed Amanda Anisimova.

Danielle Collins, Wang Qiang, Alize Cornet and Caroline Garcia were among the other winners on Wednesday, while Svetlana Kuznetsova bowed out.

SLOANE FIGHTBACK

Stephens had endured a dismal start to 2021, enduring an 0-4 win-loss record to begin the year.

The 28-year-old American was made to do it the hard way against Dodin on Wednesday, dropping the first set in a tie-break.

Stephens improved on her return in the second set, winning 73 per cent of points off Dodin's second serve before running away with the match in the last.

"It's been a rough one for me lately, so I'm really pleased to get through that, fight my way through it and make it happen somehow," Stephens said post-match.

FORMER MAJOR WINNER GONE

Two-time grand slam winner Kuznetsova was the major first-round casualty, going down 2-6 6-2 6-1 to France's Alize Cornet.

Kuznetsova, who is now ranked 35th in the world, bows out with Cornet to face ninth seed Petra Kvitova.

Collins got past France's Kristina Mladenovic 6-3 6-3 with the 40th-ranked American setting up a second-round clash with 32nd seed Veronika Kudermetova.

Wang, ranked 38th in the world, also progressed despite dropping a set in a 6-1 3-6 6-3 win over Spanish qualifier Aliona Bolsova.

SECOND-ROUND MATCH-UPS

The round of 64 will commence on Thursday, with third seed Halep to face Garcia who got past another Romanian, Mihaela Buzarnescu 6-1 6-2.

Top seed Barty will be in action against Slovakia's Kristina Kucova, while fourth seed Sofia Kenin will take on former top-10 player Andrea Petkovic.

Second seed Osaka has an assignment against 77th-ranked Australian Ajla Tomljanovic, while 14th seed Victoria Azarenka is already into the third round with opponent Laura Siegemund withdrawing after her win on Tuesday.

Serena Williams is in the Australian Open semi-finals for the first time since she last won a grand slam title, beating Simona Halep to set up a mouthwatering clash with Naomi Osaka.

The American great gained revenge for her Wimbledon final defeat to the Romanian two seasons ago as she conjured a 6-3 6-3 win on Rod Laver Arena.

Halep dropped just four games in that stunning grass-court success in 2019, the third of four grand slam finals that Williams has lost since landing her 23rd major in Australia four years ago.

The 24th title has remained frustratingly elusive, with Williams one away from matching Margaret Court's record haul, but perhaps this is the week where that changes.

She must get past Osaka, her heir apparent as the figurehead for the women's game, but Williams showed her prowess in this match, devastatingly proving a point.

Her power won out, with 24 winners to just nine from Halep, although the 33 unforced errors from Williams showed there is room for improvement in precision.

The tone was set from the first point, Williams with a brilliant forehand service return winner on the forehand side on her way to an immediate break of serve.

Halep forced her way level but Williams raised the tempo in the sixth game and a deep forehand into the Romanian's backhand corner secured a 4-2 advantage.

Williams served out the set to love at the first opportunity but then dipped early in the second set, Halep pinching a break when the American volleyed waywardly at the net.

What proved a consistent theme was Halep's struggle to hit through her opponent, and the two-time grand slam winner could not capitalise on a 3-1 lead in that second set, dropping five successive games as the 39-year-old Williams began to turn on some vintage form.

Dismissive of the often weak Halep serve, Williams swept through to the clash with Osaka.

"I definitely think this was the best match I've played this tournament for sure," Williams said. "I had to, going up against the number two in the world. I knew I had to do better and that's what I did, so I'm excited."

Looking forward to facing Osaka, Williams said in her on-court interview: "She's such a strong player on the court and such an inspirational person off the court, which I think is really cool. I've been watching her and I'm sure she's been watching me."

Former world number one Naomi Osaka is unfazed about her record at grand slams as she eyes consistency after reaching the Australian Open semi-finals.

Osaka will face either 23-time slam champion Serena Williams or Simona Halep in the semis following Tuesday's emphatic 6-2 6-2 win over Hsieh Su-wei in Melbourne.

Three-time major winner Osaka has gone on to win the title each time she has reached the quarter-finals of a slam – beating Hsieh en route to her 2019 Australian Open triumph.

Asked about the record, Osaka told reporters: "I don't really care about the stat. Just because I've only been to four quarter-finals.

"It feels something like 20. That would be cool. But four, it's not really doing too much for me.

"I would be more impressed if I didn't lose in finals. If it says 10-0 in finals. But the fact is if I don't reach the finals, I lose in the fourth round or the third round.

"For me, I'm happy to be more consistent. I think I'm being more consistent since New York, so that's the ultimate goal for me."

Osaka – in the midst of a 19-match winning streak – overpowered veteran Hsieh on Rod Laver Arena, where the Japanese star hit 24 winners and just 14 unforced errors, while she lost just two of her 25 first-service points.

It does not get any easier for Osaka, with record-chasing Williams or two-time slam champion Halep standing in the way of a trip to Saturday's decider at Melbourne Park.

"I played both of them before I think multiple times," Osaka – confident after saving two match points against Garbine Muguruza in the last 16 – said.

"Halep, I don't really like playing her. She's someone that's really tough, someone that gets the ball back every time. For me it's definitely a mental and physical battle.

"Of course, the same goes for Serena. She's Serena, someone that I feel really intimidated when I see her on the other side of the court."

Simona Halep set up a quarter-final duel with Serena Williams after showing admirable character to battle back from a set down to beat Iga Swiatek 3-6 6-1 6-4 and seal her 100th grand slam match win.

Halep and Swiatek put on a thrilling show in the night session on Sunday, as the Romanian two-time grand slam champion demonstrated her fighting spirit to come from a set down and reach the last eight.

Swiatek took charge in the first set after saving the first two break points of the contest, eventually putting herself in a commanding position as she won the 10 of the final 11 points of the set, but Halep remained focused as her 19-year-old opponent began to wobble in the second.

Halep then snuffed out any threat of a turnaround by breaking back straight after losing on her own service in the decider and she went on to set up a meeting with Williams, who had overpowered Aryna Sabalenka earlier in the day.

Naomi Osaka also advanced, though she was by no means comfortable, while Hsieh Su-wei beat Marketa Vondrousova in straight sets.

HALEP'S REVENGE

Halep's clash with Swiatek was their first since the French Open last October, when Swiatek ran out a 6-1 6-2 winner and went on to claim her maiden major title.

Revenge was on the cards at Melbourne Park and Halep got the job done impressively, showing her mettle to return from a set down.

"Well, I thought before the match that I have to be a little bit more aggressive than Paris. In Paris I have been very far back, and my ball didn't go through the court," the second seed said. "So, I thought that it's a better chance to go and hit.

"The pressure came from the way I played the last match against her. I just expected a better game from myself, which I did, and I'm really happy about that."

Halep accepts facing Williams will be an entirely different challenge, but she remains confident despite lauding the American a "legend" in her on-court interview.

"Of course it's different, she's the only one with 23 grand slams, so you cannot compare Serena with all of us, because we do not have so many grand slams," Halep added.

"But when I step on the court, it's just another opponent, and always I'm focused on myself more than I focus on who I play. We played so many times. I know what to expect. I will just try to do my game, and I will be confident."

WILLIAMS ON COURSE

All eyes are on Williams yet again, as she hopes to equal Margaret Court's record of 24 grand slam titles – and on the evidence of her latest win, she will take some stopping as she won 6-4 2-6 6-4.

Williams revealed she had to cope with a little off-court stress this week with her clothing line, and Sabalenka certainly kept the pressure up as the 22-year-old took the second set.

But Williams responded well to the seventh seed, who became the first player to take a set off the former world number one. Williams said she remained confident despite that setback.

"Like I said on the court, I just felt like even games that I lost, I was so close to winning. Not all games, but probably most of those games," she said. "I just needed to play better on the big points.  I knew that I could. I still hadn't reached my peak. I was like, 'Okay, Serena, you got this, just keep going.'"

OSAKA RELEASES HER ANGER

Osaka was in a real spot of bother against Garbine Muguruza, but saved two match points.

The 2019 champion Osaka steadied herself and felt more composed after a brief show of frustration, as she struck the ground with her racquet.

Ultimately, she emerged a 4-6 6-4 7-5 victor, and Osaka felt letting frustration get the better of her for a moment helped her cause.

"On the first match point, I was just thinking that I didn't hit a decent serve that entire game, so I should really focus on my serve," he said. "I feel like my serve stats were pretty good that set, so I was just telling myself to do better.

"Then on the second point, when the rally started, I just told myself not to push [the ball] but also don't do something crazy and make a really bad unforced error. I felt the entire match I was overthinking. There was a moment when I got angry and hit my racquet on the ground. I feel like I released a lot of the thoughts that I had. It just made me go more into instinct-based tennis."

She will face Hsieh next, the world number 71 having beaten Vondrousova – ranked 51 places higher – 6-4 6-2.