Maria Sakkari admitted she got twitchy before finishing off Simona Halep to reach the Kremlin Cup semi-finals.

The Greek star is chasing what would be just her second career title at WTA level, but the limited silverware belies her growing reputation: Sakkari has shot up to a career-high seventh in the world rankings during her best season on tour.

Looking to finish with a flourish, both in Moscow and next month at the season-ending WTA Finals, Sakkari scored a 6-4 6-4 victory over former world number one Halep on Friday.

The victory sets up a last-four clash with Ekaterina Alexandrova, after the Russian impressed a home crowd by landing a 6-3 6-4 win against top seed Aryna Sabalenka.

Yet Sakkari was almost reeled in by Halep from the point of victory in the second set, being unable to finish off the match on her own serve after building a 5-1 lead. Halep twice broke back, before dropping her own serve.

"It was a very tough match today," Sakkari said in an on-court interview. "It was the first time I'd played Simona, but I knew what to expect: she makes a lot of balls, more than any other player. I had a tough moment in the second set when I was 5-1 up, but finally, I found a way. I got a little nervous, a little bit tired.

"The last couple of months have been tough, I've been travelling a lot so haven't recovered enough. I just tried harder in the last game and just went for it."

Alexandrova's shock win over Sabalenka gave her a sixth career victory over a top-10 player. Second seed Garbine Muguruza followed Sabalenka out of the tournament, walloped 6-1 6-1 by in-form Estonian Anett Kontaveit, who has won 19 of her last 21 matches on tour, including beating Sakkari in the Ostrava final last month.

Kontaveit's semi-final opponent at the WTA 500 event will be Marketa Vondrousova, who claimed a 6-4 6-2 win over Anastasia Pavlyuchenkova.

At the Tenerife Open, Italian Camila Giorgi is the only seeded survivor in the semi-finals. The Italian fourth seed saw off Arantxa Rus 6-1 6-1, with Frenchwoman Alize Cornet and American Ann Li also among Friday's winners at the WTA 250 tournament.

Aryna Sabalenka edged past Ajla Tomljanovic in the Kremlin Cup to reach the quarter-finals in her first match since contracting COVID-19 after the US Open semi-finals. 

Top seed Sabalenka – appearing in Moscow for the first time – had not played since being downed by Leylah Fernandez, having tested positive for coronavirus on the eve of the Indian Wells Open. 

The Belarusian, who sits second in the world rankings, profited from a bye in the first round before battling past Tomljanovic 7-6 (7-2) 4-6 6-1 on Wednesday as she fired 10 aces but made 30 unforced errors. 

Sabalenka will now meet Ekaterina Alexandrova after the Russian cruised past Anhelina Kalinina 6-4 6-1, while Anastasia Pavlyuchenkova comfortably defeated Bernarda Pera 6-2 7-5. 

Number two seed Garbine Muguruza also reached her seventh quarter-final of the season as she defeated Tereza Martincova 6-4 4-6 6-3 in just under three hours in Moscow. 

Meanwhile, Elina Svitolina was shocked in the Tenerife Open as she was dumped out by Maria Camila Osorio Serrano, who succeeded 5-7 6-3 6-2 to claim her first top-10 victory. 

Svitolina was the favourite in Spain and comfortably took the first set on Tuesday. However, inadequate light stopped play and the 19-year-old Osorio responded emphatically the following day to secure a memorable triumph. 

Ann Li coasted past Varvara Gracheva 6-4 6-2 after Anna Karolina Schmiedlova had dispatched Jaqueline Cristian 6-2 7-5 in the opening match of the day. 

Xinyu Wang retired injured against Alize Cornet, who led 4-1 in the decisive set, while Donna Vekic and Irina-Camelia Begu's match was suspended for bad light with the Croatian leading by a set. 

Garbine Muguruza could not keep the momentum going at the Indian Wells Open after winning a WTA title last week and the former world number one was followed out the door by Maria Sakkari.

Muguruza, who claimed the Chicago Fall Tennis Classic, was surprisingly upstaged 6-3 1-6 6-3 by Australia's Ajla Tomljanovic in an upset on Saturday.

Tomljanovic had been 0-6 against top-10 players this year heading into the match but had just enough to edge the fifth seed and two-time grand slam champion with some timely breaks of serve. 

The world number 47 Tomljanovic is into the third round at Indian Wells for the first time in seven appearances and next faces 26th seed Tamara Zidansek. 

"I was really looking forward to playing Garbine, because I did lose [to her] the last couple of times," Tomljanovic said in her on-court interview. "I did try to focus on that one time I beat her [in 2014], and tried to channel that energy, so I was really happy that I got through today."

GOLUBIC STUNS SAKKARI

Sixth seed Sakkari – a semi-finalist at this year's French and US Opens – also fell victim to a shock result, going out 5-7 6-3 6-2 to Viktorija Golubic in their first meeting. 

The pair kept trading service breaks in the opening set, five in all, before Golubic tightened up her game for the final two sets. 

After breaking the Swiss three times in the first set, Sakkari converted just one of four break points the rest of the match. 

Golubic had lost in the first round in her previous two trips to Indian Wells but is now on to the third, where she will face Anna Kalinskaya.

ANDREESCU HOLDS OFF RISKE

Former US Open champion Bianca Andreescu saw a potential straight-sets win slip away before recovering to defeat Alison Riske 7-6 (7-2) 5-7 6-2.

Andreescu – the defending champion after the 2020 WTA Premier 1000 event was cancelled due to the coronavirus pandemic – led 4-1 in the second set but watched her advantage evaporate as Riske forced a decider, which the Canadian ended up taking comfortably as she faced only one break point in the last. 

Top seed Karolina Pliskova eased past Magdalena Frech 7-5 6-2, while third-seeded Barbora Krejcikova was pushed to a third set before prevailing 6-4 3-6 6-1 against Zarina Diyas. 

Angelique Kerber – the 10th seed and three-time major winner – went the distance to beat Katerina Siniakova 6-1 6-7 (4-7) 7-5, while 15th seed Coco Gauff downed Caroline Garcia 6-3 6-7 (2-7) 6-1 in her debut match at the tournament. 

Ons Jabeur, the 12th seed, prevailed 6-2 6-7 (5-7) 6-3 over Anastasija Sevastova and 18th seed Anett Kontaveit – Andreescu's next opponent – moved on when Martina Trevisan retired down 6-3 5-2. 

Garbine Muguruza stormed back from a set and a break down to beat Ons Jabeur and claim the Chicago Fall Tennis Classic title on Sunday.

Muguruza drew on all of her fighting spirit to claim a second title of the season and take her tally of tournament triumphs to nine, winning 3-6 6-3 6-0.

In a showdown between two players chasing a WTA Finals spot, the second seed from Spain was twice a break down in the second set after losing the first but battled back to force a deciding set and then inflicted a bagel on sixth seed Jabeur.

Victory for the second seed moved her up to sixth in the battle to play in the season-ending tournament in Guadalajara, while Jabeur is still in the mix in ninth - with the top eight qualifying.

Jabeur won the only break of the opening set with a backhand winner to move into a 3-1 lead and broke again in the opening game of the second.

Muguruza broke straight back, though, and Jabeur again failed to consolidate a break after going 3-2 up.

Two-time grand slam champion Muguruza turned the tide in spectacular fashion, winning the second set before her momentum was briefly halted by a rain delay.

Muguruza picked up where she left off in the final set, stretching her run of consecutive games won to 10 as she got her hands on another trophy.

Barbora Krejcikova explained she was hit by breathing difficulties and a spell of severe dizziness as she overcame Garbine Muguruza at the US Open.

French Open champion Krejcikova – who is making her main-draw debut at Flushing Meadows – had to hold off a fightback from former world number one Muguruza on Sunday to progress into her first US Open quarter-final with a 6-3 7-6 (7-4) victory.

However, Muguruza was left angry after Krejcikova started to take more time in between points.

After saving three set points at 4-5 down in the decider, Krejcikova went off court for medical treatment, before returning to see out the match on a tie-break.

Muguruza appeared to confront Krejcikova during the post-match handshake, and the Spaniard told the media: "I'll let you guys judge what you think about this.

"I think, between players, you know a little bit how to behave in certain moments and I wasn't very happy at the end of the match."

Krejcikova, however, explained how she had suffered during the match.

"I think I started the match really well and was playing good tennis," Krejcikova said, according to the WTA. 

"The key was to start the match well. There were a lot of breaks, which was difficult, but I was happy that I won the first set 6-3. Out of nowhere I got the lead 4-0 and then things started to get complicated.

"Garbine started to raise her level and I was expecting that. At the end I was really struggling and I feel really bad right now.

"I don't really know what happened, but I couldn't breathe. I started to feel dizzy and the whole world was shaking. It never happened to me before."

Krejcikova also needed medical attention after the match and did not hold a post-match news conference.

The Czech has now won 29 of her last 32 matches and will face Aryna Sabalenka, the highest seed remaining at Flushing Meadows, in the quarter-finals. 

Crowd favourite Bianca Andreescu was made to work as she opened her defence of the National Bank Open title she won two years ago but the Canadian eventually prevailed in Montreal. 

Andreescu defeated Harriet Dart 6-1 3-6 6-3 in just over two hours in her first match since falling to Alize Cornet in the opening around at Wimbledon. 

That was the latest in a disappointing string of results for Andreescu, who also departed Roland Garros after one match, but the world number eight got back on track Tuesday. 

"Playing at home is so, so awesome," Andreescu said in her on-court interview. "You guys [the fans] show me so much love, especially tonight. I've never had this kind of support before, so I'm so, so grateful."

While Andreescu was able to navigate a challenging opener, three other seeded players were not as fortunate. 

Katerina Siniakova downed fifth seed Garbine Muguruza 6-2 0-6 6-3, while Camila Giorgi ousted ninth seed Elise Mertens 6-3 7-5 and Liudmila Samsonova defeated 12th seed Elena Rybakina 6-4 5-7 6-4.

Having a better time of it were seventh-seeded Petra Kvitova, the 2012 tournament champion, and number 10 seed Anastasia Pavlyuchenkova, who won by identical 6-4 6-4 scorelines against Frenchwomen Fiona Ferro and Carolina Garcia, respectively. 

Eighth-seeded Victoria Azarenka waited out a rain delay to cruise past 2013 finalist Sorana Cirstea 6-2 6-2 in the final match of the day. 

In other action, 15th seed Coco Gauff handled Anastasija Sevastova 6-1 6-4 while her countrywoman Danielle Collins continued rolling after her title in San Jose last week, rallying past Jil Teichmann 4-6 6-1 6-3 for her 11th consecutive match win. 

Two more Americans, Sloane Stephens and Jessica Pegula, prevailed in three sets as well. 

Johanna Konta returned to the court after missing Wimbledon and the Tokyo Olympics due to coronavirus-related issues and advanced when Zhang Shuai was forced to retire up 6-4 2-5 with a leg injury. 

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

The surprising 6-1 6-4 loss that a lacklustre Osaka suffered on Tuesday could be explained away by the fact the 23-year-old had not played any competitive tennis since pulling out of the French Open at the end of May.

All the same, it was a major upset as world number 42 Vondrousova took out the highest remaining seed in the draw – the Japanese star who lit the Olympic cauldron on Friday.

Osaka's exit, after previous shock defeats for top seed Ash Barty and number three Aryna Sabalenka, has raised the prospect of a shock champion, just as occurred five years ago at the Rio Games when Monica Puig of Puerto Rico caused a sensation.

Now at the quarter-final stage, there is one former grand slam champion left in the field and two finalists at that level, but it really looks like anyone's title.

VONDROUSOVA SENSES AN OPPORTUNITY

It was remarkably straightforward for Vondrousova at Ariake Tennis Park, as she cruised through the opening set and soon reeled in Osaka's early break in the second.

Osaka saved two match points when serving to stay in the contest, but not a third, planting a backhand wide.

Considering Vondrousova reached the French Open final two years ago, in front of packed grandstands rather than the empty seats in Tokyo, it was no surprise she hesitated when asked whether this win over Osaka was the biggest of her career. It probably doesn't have that cachet, good a win though it was.

"Of course it's one of the biggest," Vondrousova said.

"Naomi is a great player, she has so many grand slams, so I knew it would be a tough match. But I'm just very happy with my play. I played amazingly in the first set, and then the second set was really tough. I'm just happy to be through.

"I think she was struggling a bit with my serving. Also, I use drop-shots very well. I'm just very happy with my game today."

She faces Spain Paula Badosa next and said: "It's very open now. I think every girl is playing really well. Now it's the quarter-final, so we'll see."

HAS SVITOLINA'S TIME ARRIVED?

A fixture in the top 10 over recent seasons, Svitolina has been unable to transfer her regular tour form onto the major stage on a consistent basis.

Maybe the Olympics will be a platform towards success on that stage, with Svitolina now the highest seed remaining in the draw, at number four. The Ukrainian is also on a high on the personal front, having married French tennis star Gael Monfils shortly before heading to Tokyo.

Two semi-finals, at Wimbledon and the US Open in 2019, have been her deepest runs in the majors, and this season has been one of diminishing returns, with a fourth-round run in Australia followed by a third-round Roland Garros exit and a round-two loss at Wimbledon.

Svitolina beat Maria Sakkari of Greece 5-7 6-3 6-4 on Tuesday, setting up a quarter-final against Italian Camila Giorgi who won 6-4 6-2 against Wimbledon runner-up Karolina Pliskova.

"I don't think I'm a favourite because there are lots of good players here and everyone is quite equal," Svitolina said.

A MUG SHOT?

Should Spain's Garbine Muguruza be considered the favourite from this point? With French Open and Wimbledon titles in her trophy room, Muguruza has shown she has what it takes to triumph on a big stage, and a clinical 6-4 6-1 win over Belgian Alison Van Uytvanck on Tuesday was just the job.

She goes on to face Elena Rybakina of Kazakhstan, who edged past Croatian Donna Vekic.

Belinda Bencic of Switzerland caused a surprise by ousting the in-form reigning French Open champion Barbora Krejcikova, springing a 1-6 6-2 6-3 win that means there will be no repeat of the Roland Garros final in the quarter-finals.

That had been on the cards, but Bencic will be the player who takes on Anastasia Pavlyuchenkova for a place in the final four.

Pavlyuchenkova scored an impressive 6-1 6-3 victory over Sara Sorribes Tormo of Spain, the player who knocked out Barty in round one.

Russian Olympic Committee's Pavyluchenkova is looking to harness the form that took her to a maiden slam final, describing her Paris run as "a great experience to have".

"But every week is a new week and this is a new event," said the 30-year-old. "The Olympic Games is a very special event. It's different. It's nothing like the others."

Ons Jabeur ended the Wimbledon title hopes of Garbine Muguruza with a Centre Court triumph she hailed as the biggest moment yet in her career.

The Tunisian followed up a second-round win over veteran five-time champion Venus Williams by eliminating 11th seed Muguruza, brilliantly plotting her path through a treacherous draw.

A 5-7 6-3 6-2 victory for 21st seed Jabeur sets up a stellar fourth-round clash with Iga Swiatek, the 20-year-old Polish rising superstar who scored a sizzling 6-1 6-0 win earlier against Irina-Camelia Begu.

Swiatek won the French Open last year and is the seventh seed at Wimbledon.

Muguruza found a way to win through the opening set against Jabeur, but thereafter she was second best against a player who won her first career title last month in Birmingham.

That Birmingham success had been coming for a long time, with Jabeur becoming an increasing force on the women's tour, but she came to Wimbledon with nothing to call upon in terms of previous success at the grass-court grand slam.

Two first-round exits came either side of a 2018 second-round loss, but Jabeur looked right at home on the big stage against Muguruza, the 2017 champion and former world number one.

"I'm good. I can play another match now, you know!" said Jabeur, almost breathless, immediately after the contest.

"I'm very happy and honestly this is the first time I've been on Centre and it was amazing energy guys, thank you."

Interviewed in front of a crowd who took to her tennis and warm personality, Jabeur was asked whether this was the best day of her career.

The 26-year-old responded: "It is! Seriously. I'm not saying this so you guys can cheer for me for the next round, but this is my favourite centre court I play. The energy's amazing. I'm so, so, so happy."

Jabeur could not take a first match point but then lashed down a serve that Muguruza could barely get a racket to and followed that point by finishing off a baseline rally with a thumping forehand winner into the left corner.

It was some victory for the player who became the first Arab winner on the WTA Tour with that Birmingham final triumph over Daria Kasatkina.

Against Muguruza, Jabeur fired 44 winners against 27 unforced errors, a healthy ratio, and won 18 of 22 points when she went to the net.

As Muguruza trudged off, disappointed, Jabeur reflected on how the match went better than their previous meeting, when the Spaniard won in a deciding-set tie-break at Hobart last year.

"She plays unbelievably on grass and everybody knows that," Jabeur said. "I lost against her last time, but this was my revenge here – in a nice way.

"I tried my best. It was difficult in the first set, we weren't reading our serves, but then after the second set I tried to stay more calm and enjoyed playing here.

"I was more aggressive, trying to do some drop shots and going into the net.

"Sometimes when I play loose and good my forehand gets better, and everything gets better."

Belinda Bencic let anger fuel her progress to the semi-finals of the bett1open in Berlin on Friday.

Bencic – the fifth seed – needed a third-set tie-break to see off Ekaterina Alexandrova 6-4 4-6 7-6 (7-4).

The Swiss will face Alize Cornet at Steffi Graff Stadion in Saturday's semi-final, after the latter upset two-time grand slam winner and world number 13 Garbine Muguruza – similarly going the distance to prevail 4-6 6-3 7-6 (7-5) and saving match point at 5-4 in the tie-break.

Bencic had lost two of her previous three encounters with Alexandrova and conceded to having problems with her opponent's playing style after a fired-up performance at the WTA 500 event.

"I have to get mad," she said. "When I'm mad, I play better, I'm just hitting the ball. So I'm trying to get mad on court."

"I definitely don't like playing her," said Bencic afterwards. "There's not so much rhythm, she's very aggressive player, it's tough to stay in the rally. I would say I'm more relieved [to reach the semi-finals].

The other semi-final pits two-time slam champion Victoria Azarenka against qualifier Liudmila Samsonova.

Former world number one Azarenka battled to see off Karolina Pliskova's conqueror Jessica Pegula 6-2 5-7 6-4, gaining a measure of revenge over a player who dumped her out in the first round of the Australian Open this year.

Samsonova stunned Madison Keys, with a deciding tie-break again required, albeit one that was emphatically dealt with as the world number 106 won 7-6 (7-4) 2-6 7-6 (7-0).

Jessica Pegula got the better of Karolina Pliskova once again as she knocked the fourth seed out of the bett1open on Thursday.

The American beat the former world number one 7-5 6-2 in Berlin, setting up a quarter-final clash with Victoria Azarenka.

It is the fourth time this season Pegula has defeated Pliskova.

Azarenka was also a straight-sets winner, overcoming Angelique Kerber in a battling 6-3 7-5 victory.

The two-time Australian Open champion was 4-1 down in the second set but roared back to prevail over Kerber for the 10th time in 11 matches.

Garbine Muguruza enjoyed a 6-4 6-3 victory over Elena Rybakina and will take on Alize Cornet next, while Ludmilla Samsonova downed Veronika Kudermetova by the same scoreline and will now face Madison Keys.

Garbine Muguruza, Victoria Azarenka and Angelique Kerber all sailed through at the bett1 Open on Tuesday as eighth seed Karolina Muchova crashed out in the first round.

The three former world number ones each made relatively light work of their opening clashes in Berlin, with Muguruza seeing off Sorana Cirstea 6-3 6-2.

Muguruza, the 2017 Wimbledon champion, expressed satisfaction with her performance on a return to the grass courts, with that part of the season wiped out in 2020 by the coronavirus pandemic.

"Very pleased," Muguruza said on court after going 24-8 on the season.

"You never know how it's going to go in the first match, especially on grass after two years, so I'm very excited to win in two sets against Sorana.

"We've played many times, and it's always difficult."

She will next face Elena Rybakina who, after beating Serena Williams en route to the French Open quarter-finals, came from a set down to see off Shelby Rogers.

Azarenka was a 6-4 7-6 (7-2) winner over Andrea Petkovic, and the two-time Australian Open champion will now face Kerber for a place in the last eight.

Kerber routed Misaki Doi 6-2 6-1 in a match that lasted only an hour but has lost nine of her previous 10 meetings with Azarenka.

The 2018 Wimbledon champion said: "I will try to play my game, and try to take another chance, and play as many matches as I can before I go to Wimbledon.

"It's another good match at a high level, and this is why I'm here. The draw is really strong, so it's good to have another good match."

Muchova, though, fell at the first hurdle. The Czech suffered an upset in the third round of the French Open at the hands of Sloane Stephens and lost in three sets in the German capital to Veronika Kudermetova after two hours and 27 minutes.

Elsewhere in the draw, there were wins for Petra Martic, Liudmila Samsonova and Jessica Pegula, whose opponent Hailey Baptiste retired in the first set.

Garbine Muguruza eased into the second round of the Internazionali BNL d'Italia on Tuesday thanks to a comfortable victory over lucky loser Patricia Maria Tig, though Belinda Bencic was the biggest casualty on a rain-interrupted day.

Spaniard Muguruza was due to face Anastasia Pavlyuchenkova until the Russian withdrew due to an abdominal issue, giving Tig a reprieve and the chance of an upset.

But Muguruza won all but three games in a comprehensive 6-1 6-2 victory that required little more than an hour on court as the former world number one went to 22-6 for the season.

Conditions were not great as drizzle persisted for much of the match, but Muguruza was grateful to progress after a generally testing day.

"It was a weird day," the 12th seed said afterwards. "I woke up [and the weather was] sunny, had an opponent. Then it turned out I had another opponent and it was raining the whole match. We had a little bit of everything!

"But, Rome, it's such a familiar tournament. I played here so many times, I've had nice matches. I love this clay, the red clay. It's familiar to me. I'm just looking forward to getting as many matches as possible."

Bencic will not be joining her in the next round, as she became the highest seed to be eliminated on the day in a 6-3 6-4 defeat to Kristina Mladenovic.

The two played each other under two weeks ago in the first round of the Madrid Open, with Bencic victorious, but Mladenovic got her revenge as she capitalised on her opponent's seven double faults.

Like Tig, Sloane Stephens was also competing as a lucky loser as she came up against compatriot Madison Keys, though the outcome was no different.

Keys claimed only her second win in six meetings with Stephens but had to come from behind as she eventually clinched it 4-6 6-2 7-5 after two-and-a-half hours on court to set up a clash with 15th seed Iga Swiatek.

Elise Mertens, the 14th seed, was also dumped out of the competition, losing out 4-6 6-2 6-3 to Veronika Kudermetova, whom she had beaten in straight sets in their three WTA Tour contests before this one.

Veteran Kazakh Yaroslava Shvedova, ranked 665 in the world, awaits top seed Ashleigh Barty after the 33-year-old showed character to fight back and beat Martina Trevisan 0-6 7-6 (7-4) 7-6 (8-6), while Nadia Podoroska set up a second-round clash with Serena Williams after seeing off Laura Siegemund 2-6 7-6 (7-3) 6-1.

Jil Teichmann saved six match points in a stunning defeat of Elina Svitolina before Ash Barty breezed into the second round of the Madrid Open on Thursday.

Teichmann produced an astonishing fightback to beat fourth seed Svitolina 2-6 6-4 7-6 (7-5) at the Caja Magica.

Unseeded Swiss Teichmann came from a set and a break down to claim the scalp of the world number five, who squandered a commanding 5-1 lead in the final set.

Svitolina saw six match points come and go in an incredible deciding set, opportunities she was left to rue when the 40-ranked Teichmann won a tie-break to end a contest that took two hours and 33 minutes to settle.

World number one Barty extended her winning run on clay to 12 matches with a 6-2 6-1 success over Shelby Rogers.

Barty claimed her third title of the year in Stuttgart last weekend and the Australian needed just an hour to send Rogers packing, losing just two points on her first serve and not facing a single break point.

French Open champion Iga Swiatek was also an emphatic winner, easing past another American in the form of Alison Riske 6-1 6-1.

Swiatek, making her debut in this tournament, has won 16 consecutive matches on clay after blowing Riske away.

Defending champion Kiki Bertens beat 15-year-old Victoria Jimenez Kasintseva 6-4 6-0, while Petra Kvitova progressed when opponent Marie Bouzkova retired due to hand injury after the Czech won the first set.

Garbine Muguruza was forced to withdraw ahead of her meeting with Sloane Stephens due to a leg injury. Belinda Bencic, Angelique Kerber and Johanna Konta were among the other winners in the Spanish capital.