World number one Iga Swiatek commenced her San Diego Open campaign with a hard-fought three-set victory over Chinese lucky loser Zheng Qinwen in rainy conditions on Thursday.

The 2022 French Open and US Open champion triumphed 6-4 4-6 6-1 in two hours and two minutes, bouncing back strongly after losing the second set.

Zheng's power and forehand top spin proved challenging for the Pole, who was solid from the baseline to secure her 11st tour quarter-finals appearance this season.

The Chinese had broken Swiatek to lead 1-0 in the third set, but the top seed responded in trademark style, improving her record in the United States this season to 21-1.

Swiatek will take on eighth seed Coco Gauff in the quarter-finals, with the match-up marking a re-match of this year's French Open final.

Gauff worked her way into the last eight with a 6-4 4-6 6-3 victory over 2019 US Open champion Bianca Andreescu.

The 18-year-old American also had to fight back from a set down in the third set to win in a match that lasted just over two-and-a-half hours.

Third seed Aryna Sabalenka fought back from a lopsided opening set to knock out American Sloane Stephens 1-6 6-3 6-2 in two hours and one minute. The Belarussian will take on Donna Vekic in the next round.

Second seed Paula Badosa eased into the last eight, winning in 53 minutes against American qualifier Louisa Chirico 6-0 6-3. Badosa will face Danielle Collins in the quarter-finals.

Madison Keys triumphed over eighth seed Daria Kasatkina 6-4 6-3 in one hour and 27 minutes to secure a quarter-final date with fourth seed Jessica Pegula.

Andy Murray overturned a first-set deficit to defeat Pedro Cachin gripping 2-6 7-5 7-6 (7-3) and book his spot in the quarter-finals of the Gijon Open.

The three-time grand slam champion lost a 56-minute opening set but showing his trademark doggedness to defeat his Argentine opponent and earn a fourth Tour-level last-eight berth of the season.

It sets the Briton up with a last-eight encounter against Sebastian Korda after the unseeded American delivered the upset of the day to knock out third seed and home favourite Roberto Bautista Agut in a 5-7 6-4 6-4 triumph.

Elsewhere, first seed Andrey Rublev saw off a fightback from Ilya Ivashka to also book his place in the quarter-finals, with his reward a tie against Tommy Paul.

At the Firenze Open, top seed Felix Auger-Aliassime saw off a second set scare from Germany's Oscar Otte, with the Canadian ultimately triumphing 6-4 6-7 (2-7) 6-2.

He will meet eighth seed Brandon Nakashima, who ran out comfortably in straight sets against Altug Celikbilek with a 6-3 6-4 win.

Third seed Lorenzo Musetti also made smooth work on his own turf, with a 6-3 6-0 demolition job against Bernabe Zapata Miralles, to set up an encounter in the last eight with Mackenzie McDonald.

Number two seed Anhelina Kalinina cruised through to the last eight of the Transylvania Open on Thursday thanks to a straight sets victory over Ysaline Bonaventure.

The Ukrainian barely had to break sweat on her way to a 6-3 6-2 triumph to set up a quarter-final meeting with Anna Blinkova, who beat Xinyu Wang 6-4 2-6 6-1.

Fourth seed Anastasia Potapova had an equally comfortable time in her last-16 match against Viktorija Golubic in Cluj, strolling to a 6-2 6-3 win.

Xiyu Wang, seeded seventh, had a tougher time in her meeting with Elena-Gabriela Ruse, the Chinese player ultimately overcoming her Romanian opponent 6-1 6-7 (8-10) 7-6 (8-6).

In Thursday's other match, Nuria Parrizas Diaz beat Dalma Galfi 6-1 6-4.

Coco Gauff won the battle of the American teenagers as she progressed into the San Diego Open second round with a 6-3 6-3 over Robin Montgomery on Wednesday.

The 2022 French Open finalist beat fellow 18-year-old Montgomery in a rain-affected match in one hour and 23 minutes, to clinch a last-16 clash with Bianca Andreescu.

The match marked Gauff's first game on tour since losing to Caroline Garcia in the US Open quarter-finals last month, although she had to endure an overnight rain delay, resuming on Wednesday up 6-3 3-2.

Gauff only needed 20 minutes on Wednesday to close out the victory, finishing the match with 3-0 aces, winning 76 per cent on her first serve and converting four of seven break points.

Croatian qualifier Donna Vekic continued her strong run with a 6-3 6-2 win over 2022 US Open quarter-finalist Karolina Pliskova. Vekic moved into the third round, having beaten Maria Sakkari in the first round too.

Fourth seed Jessica Pegula eased her way into the third round with a 6-3 6-1 victory over wild card Coco Vandeweghe in only 69 minutes. Pegula can secure her first WTA Finals qualification this week.

Danielle Collins was another American victor, triumphing 6-2 6-4 over Italy's Martina Trevisan in one hour and 27 minutes, reaching her third quarter-final of the year.

Coco Gauff believes her and fellow teen Robin Montgomery are products of Venus and Serena Williams' legacy as the Roland Garros runner-up looks to inspire the next generation of African-American talent.

The two 18-year-old Americans collided in the opening round of the San Diego Open, with Gauff prevailing 6-3 6-3 in what was her first match since defeat by Caroline Garcia in the US Open quarter-finals last month.

This season's Roland Garros finalist is widely believed to be the next dominant player from her nation following the retirement of Serena Williams at Flushing Meadows.

Along with sister Venus, the Williams sisters won a combined 30 major singles titles during their highly decorated careers, as well as 14 grand slam triumphs in women's doubles, in which they are also the only pair to win a career golden slam.

And Gauff hopes she can follow the sisters' well-trodden footsteps, while also going on to serve as an inspiration herself.

"It definitely affects the future a lot," she said during her post-match interview. "If Serena and Venus saw this today; two 18-year-olds - both African-American - playing on the WTA 500 level - I think they would be proud.

"I think both of us are products of their legacy. I'm grateful that I had those examples to follow after, and I hope I can be an example myself."

On the match, she said: "It was the first time playing someone younger than me in probably at least seven years. It was definitely a different feeling for me.

"I know Robin very well, we went on a couple of USTA trips back when we were about eight-years-old. She played really well, I expected a good level from her. I was pretty impressed with how well she was striking the ball; it was difficult for me."

Magda Linette was the highest-profile casualty at the Transylvania Open on Wednesday after suffering a straight-sets defeat against Xinyu Wang.

Four of the seeded players have now fallen at the first hurdle in Cluj, with Lucia Bronzetti also joining Linette, Ana Bogdan and Marta Kostyuk in suffering early exits.

Fifth seed Linette was beaten 6-2 6-4 by Wang, while ninth seed Bronzetti went down 4-6 6-2 6-4 against world number 89 Dalma Galfi.

Anna Bondar is through to the quarter-finals, though, with the eighth seed enjoying a 7-6 (7-3) 6-4 victory over Harriet Dart.

Jasmine Paolini took just 58 minutes to wrap up a resounding 6-4 6-1 win over Dayana Yastremska.

Next up for the Italian is a last-eight showdown with Wimbledon quarter-finalist Jule Niemeier, who overcame Kamilla Rakhimova 6-4 6-4.

Roberto Carballes Baena stunned second seed Matteo Berrettini in a thriller at the Firenze Open, winning 5-7 7-6 (7-5) 7-5 in the last 16.

Berrettini edged a thrilling first set 7-5, which clocked in at 75 minutes long, and faced another stern challenge in the second.

At one point trailing 4-2, Berrettini fought back to set-up a tie-breaker that was equally tight, with Carballes Baena fighting back from 4-2 down to force a decider.

With the clock past the three-hour mark, Carballes Baena capped off a remarkable comeback in the third set to send Berrettini tumbling out of the tournament, coming back from a break down once again.

Earlier in the day, fourth seed Maxime Cressy was eliminated by American compatriot J.J. Wolf after a 6-3 6-4 defeat and fifth seed Aslan Karatsev was also eliminated, losing 6-1 6-7(6-8) 6-1 in a two-and-a-half-hour showdown.

At the Gijon Open, second seed Pablo Carreno Busta sealed a spot in the quarterfinals with a 6-4 7-6(3) victory over Brazilian Thiago Monteiro, forcing three errors from Monteiro in the second-set tie-breaker.

Fifth seed Tommy Paul secured safe passage to the quarter-finals, beating Nicolas Alvarez Varona 6-3 7-6 (7-3), with Pedro Cachin and Sebastian Korda among the day's other winners.

Novak Djokovic will receive no assistance from Tennis Australia in lobbying for his ban to the country to be lifted for next year's Australian Open, says boss Craig Tiley.

The Serbian was deported after having his visa cancelled on public health grounds ahead of this year's tournament having been initially allowed to enter the country in spite of his unvaccinated status, amid widespread furore over his apparent flaunting of strict regulations.

TA played a part in securing his arrival, with Djokovic under the belief a medical exemption would have allowed him to compete, and the 21-time grand slam champion indicated his hope to return despite a three-year ban from the nation.

Now, Tiley has said the governing body will not advocate for his return, and that it will ultimately be a decision for the Australian government.

"What we're saying at this point is that Novak and the federal government need to work out the situation, and then we’ll follow any instruction after that," he stated at the tournament launch.

"I did spend some time with Novak at the Laver Cup. We spoke generally. He said that he'd obviously love to come back to Australia, but he knows it’s going to be an ultimate decision for the federal government.

"He's accepted that position. It's a private matter between them. It's not a matter we can lobby on.”

The deadline for tournament applications is in December - and Tiley also revealed Russian and Belarusian players will be allowed to feature, albeit as independent athletes under a neutral flag.

The 2023 Australian Open is the first since the former invaded Ukraine earlier this year, and while Wimbledon barred players from both countries, they were permitted to compete at the French Open and US Open.

"At this point, Russian and Belarusian players will be eligible to play in the Australian Open," he said. "The only difference will be that they cannot represent Russia, cannot represent the flag of Russia.

"They cannot participate in any activity such as the anthem of Russia, and they have to play as independent players under a neutral name. But they will be welcome to the Australian Open in January."

Donna Vekic produced a spectacular second set to shock world number seven Maria Sakkari 7-6 (7-3) 6-1 in the first round of the San Diego Open on Tuesday.

After a hard-fought first set where both women were able to convert one of their four break point opportunities, Vekic took control in the tie-breaker and carried that momentum in the second set.

Vekic won 65 per cent of her service points in the second set, while Sakkari could only muster a 47-per-cent success rate, despite having a significant edge in first-serve accuracy (79 per cent to Vekic's 53 per cent).

The Croatian only had two break point opportunities, and that is all she needed, taking both to run away with one of the biggest wins of her career.

Vekic will play Karolina Pliskova in the second round after the Czech defeated America's Caroline Dolehide 6-3 6-4.

Pliskova, ranked 22nd in the world, had no issue with the world number 181 in one of Tuesday's biggest mismatches, nabbing a break-to-love in the first set before taking a quick double-break to begin the second.

World number 11 Daria Kasatkina was too strong for Leylah Fernandez, cruising to a 6-2 6-2 victory in exactly one hour.

Sloane Stephens earned a shot against world number five Aryna Sabalenka in the second round after getting the better of Switzerland's Jil Teichmann 6-1 7-6 (7-2).

World number 13 Garbine Muguruza was clearly not at 100 per cent, retiring hurt after losing the first five games of her match against China's Qinweng Zheng, and Coco Gauff will resume her contest against Robin Montgomery leading 6-3 3-2 after rain halted the action for the day.

Andy Murray recovered from a break down in the first set to surge into the second round of the Gijon Open with victory over Alejandro Davidovich Fokina.

The three-time grand slam champion trailed 4-2 and 30-40 in the opener, but he saved break point with a brilliant volley before going on to hold and take command.

Murray won 10 of the next 13 games thereafter to claim a 7-5 6-2 win, and the former world number one felt Davidovich Fokina's frustration played a key role in the turnaround.

"In the first set, he was playing much better than me," said Murray, seeking his first ATP Tour title since prevailing in Antwerp in 2019.

"He had a lot of chances to get the second break of serve, and I managed to stay tough in those moments. At the 4-3 game, he played a bad game to give me the break back, and after that I started to play a little bit better.

"I think he was a bit frustrated, and then in the second set his level dropped a little bit, but the end of the first set was very important because he was playing very well and it was a difficult first set."

Murray will face either Pedro Cachin or qualifier Alexey Vatutin in the second round. Davidovich Fokina's fellow Spaniards Feliciano Lopez and Albert Ramos-Vinolas lost to Ilya Ivashka and Marcos Giron respectively. There was victory for one home hope, though, as Nicolas Alvarez Varona moved into round two.

At the Firenze Open, Alexander Bublik secured his 100th Tour-level win with a straight-sets victory over Cristian Garin, while Mikael Ymer thrashed Tim van Rijthoven 6-1 6-2.

Oscar Otte and Brandon Nakashima were also victors in Florence on Tuesday.

Anhelina Kalinina progressed to round two of the Transylvania Open after opponent Eugenie Bouchard retired injured in Cluj.

Ukrainian world number 45 Kalinina took the opening set 6-3 before a hip injury prevented Bouchard from continuing.

The Canadian revealed she had retired as a precaution having undergone an MRI on Monday, and did not wish to aggravate the issue any further.

"I'm just disappointed to have ended my tournament in Romania this way because I really loved being here in Cluj," she said. "I pulled my hip flexor a few days in practice. I tried everything to be ready for this match.

"I got an MRI yesterday, and didn't show anything too bad, so I thought I could play. But it was getting worse as the match went on. To avoid a big injury, I figured it would be best to retire.

"I absolutely hate retiring, I wish I could've done better here, but I hope to be back."

Fourth seed Anastasia Potapova beat Ann Li 6-2 7-6 (7-5) to set up a clash with Viktorija Golubic, who overcame Diane Parry in straight sets.

Seventh seed Xiyu Wang advanced in straight sets against home favourite Jaqueline Cristian, while Harriet Dart required just 64 minutes to wrap up a commanding 6-2 6-0 victory over Oceane Dodin.

In a first-round clash between two of the world's top-20, Danielle Collins eliminated Caroline Garcia 6-2 7-6 (7-4) from the San Diego Open on Monday.

Garcia, the world number 10, entered the contest off back-to-back losses for the first time since March, and Collins made it three in a row as she was just a little too good with both her serving and return game.

Collins won 63 per cent of her service points, with Garcia at 52 per cent, and she ended up securing five breaks in the match.

She will play Martina Trevisan in the second round after the Italian defeated Colombian qualifier Camila Osorio 6-3 6-4.

Neither player had an ace in the match, but the big differentiating factor was Trevisan's ability to win points off her second serve, converting 50 per cent of her chances while Osorio won only one of nine (11 per cent).

The only qualifier of the day to get a win was Louisa Chirico, who beat fellow American Alison Riske-Amritraj 1-6 7-5 7-6 (7-5).

Chirico, the world number 196, will be rewarded for her win with a showdown against world number four Paula Badosa.

Madison Keys had no issues dealing with Australian qualifier Ellen Perez 6-1 6-4 in just over an hour, and Coco Vandeweghe defeated Sofia Kenin 6-1 1-6 6-4.

In the last match of the night, Canada's Bianca Andreescu won a two-hour-and-40-minute battle against Russia's Liudmila Samsonova 7-6 (7-1) 4-6 6-2.

Seeds Ana Bogdan and Marta Kostyuk crashed out of the Transylvania Open in the first round.

Home hope Bogdan, seeded third in Cluj-Napoca, was beaten in straight sets by Jule Niemeier, who showed the quality that helped her reach the last eight of Wimbledon in a 7-6 (7-5) 6-2 win.

Ukrainian Kostyuk, meanwhile, lost in three sets to Jasmine Paolini.

The sixth seed took a tight first set but Paolini broke Kostyuk five times thereafter en route to a 5-7 6-3 6-4 triumph.

Eighth seed Anna Bondar enjoyed a better day, prevailing 6-4 6-2 over Elina Avanesyan, while there were also wins for Dayana Yastremska, Anna Blinkova and Ysaline Bonaventure.

Dominic Thiem produced a dominant display to cruise past Joao Sousa in the duo's first-round clash at the Gijon Open, only dropping two games for just the second time in his career.

The 2020 US Open winner did not face a single break point in his one-sided 6-2 6-0 victory on Monday, reaching the last 16 after 62 minutes.

It is just the second time in the Austrian's career he has lost as few as two games in a completed ATP-level match, having previously done so against Jaroslav Pospisil in 2013 (in a 6-1 6-1 win).

"Especially with the forehand, it was really good for basically the first time [since my injury]," Thiem said afterwards. "I'm very happy about it. This way is right, the direction is right."

Meanwhile, Argentina's Sebastian Baez was forced to retire when a set down to France's Constant Lestienne, and fifth seed Tommy Paul eased past 16-year-old home hope Martin Landaluce in straight sets.

Only one seed was in action at the Firenze Open on Monday, with Aslan Karatsev advancing courtesy of a walkover following an injury to Tallon Griekspoor. 

Barbora Krejcikova completed a fairytale home tournament as she won the Ostrava Open by beating world number one Iga Swiatek 5-7 7-6 (7-4) 6-3 in Sunday's final.

Krejcikova lifted the Tallinn Open last week for her first title of the season, and made it two from two with an impressive run to the final before a hard-fought triumph over Swiatek to earn a ninth straight victory and another championship trophy.

Swiatek herself had won 10 matches on the bounce, and the Pole raced to five of the first six games to lead the opener 5-1, though Krejcikova rattled off four straight games to level it up. 

However, after making it 6-5, Swiatek then found a crucial break to clinch the first set.

The second went all the way to a tie-break, which Krejcikova took the ascendancy of by putting herself 6-1 up, and despite a late Swiatek rally, the Czech 26-year-old finally levelled the match after watching four set points come and go.

In the decider, neither could find a break until the eighth game, with Krejcikova doing so to put herself within a game of winning.

And in an extraordinary final stand, Swiatek survived five championship points before her resistance was ultimately broken to deny her an eighth final victory in 2022.

It was Krejcikova's first win against Swiatek, having lost their previous two meetings, as the seventh seed sealed an incredible victory.