American teenager Coco Gauff showed why she deserves to be at this year's WTA Finals with a commanding 6-0 6-3 victory over Martina Trevisan at the Guadalajara Open.

The fifth seed clinched her maiden spot at the season-ending WTA Finals on Wednesday and backed that up by securing her third WTA 1000 quarter-final on Thursday.

Gauff reeled off the first nine games of the match against Trevisan, where she triumphed in one hour and one minute. The 18-year-old came under pressure from Trevisan, who generated nine break points for the match but Gauff saved all bar one of them.

World number one Iga Swiatek (47) is the only player to have won more matches this year in straight sets than Gauff (32).

Gauff will face Victoria Azarenka in the quarter-finals after the Belarusian toppled 13th seed Madison Keys 6-4 6-7 (4-7) 6-1 in two hours and 13 minutes.

Two-time Australian Open winner Azarenka swept aside Keys in 32 minutes in the third set after a titanic battle in the opening two frames, winning 26 of the 37 final-set points. Azarenka's quarter-final appearance is her 34th since 2009, with only four players having more during the span; Agnieszka Radwanska (42), Simona Halep (39) and Caroline Wozniacki (36).

Third seed Jessica Pegula advanced to the last eight with a 6-4 6-4 victory over former US Open champion Bianca Andreescu. 

The American, who survived three match points against Elena Rybakina on Wednesday, trailed early against the Canadian but took control of the match. Pegula will face Sloane Stephens in the quarter-finals after she toppled 2022 US Open semi-finalist Caroline Garcia 7-6 (8-6) 7-5.

On the day her WTA Finals berth was confirmed, seventh seed Daria Kasatkina lost 6-2 2-6 6-3 to Anna Kalinskaya in two hours and 14 minutes.

Fourth seed Maria Sakkari fought back to win 5-7 6-3 6-3 over 14th seed Danielle Collins, while Marie Bouzkova copped a bagel before triumphing 0-6 7-5 6-3 over Liudmila Samsonova.

Sakkari will next meet eighth seed Veronika Kudermetova who beat Jelena Ostapenko 6-4 6-4. Bouzkova will take on Kalinskaya in the last eight.

It was a great day for the highly ranked Americans at the Guadalajara Open on Wednesday, headlined by world number five Jessica Pegula and her 2-6 6-3 7-6 (10-8) comeback win over Wimbledon champion Elena Rybakina.

Pegula, who is now locked into the top-eight and therefore will qualify for the WTA Finals, struggled to win points on her serve in the opening set, but raised her 57 per cent success rate up to 69 per cent in the second set, and 66 per cent in the decider.

The American had to come from a break down in the second set to keep her tournament alive, and she will now face Canada's Bianca Andreescu in the third round.

Meanwhile, fellow United States star Coco Gauff was too good for Italy's Elisabetta Cocciaretto, winning 7-6 (7-1) 6-3 to book a third-round clash with another Italian, Martina Trevisan, who earned her way there with a 6-0 4-6 6-3 win over Katerina Siniakova.

The other two seeded Americans were also successful, with 13th seed Madison Keys coming from a set down to defeat Ajla Tomljanovic 3-6 6-4 6-3, and 14th seed Danielle Collins repelled the challenge of Magdalena Frech 6-3 6-4.

There were positive signs for former world number five Eugenie Bouchard, who ended up losing, but showed she still has her talent by taking a set off world number 23 Jelena Ostapenko in a 7-5 2-6 6-1 result.

Russian pair Anna Kalinskaya and Liudmila Samsonova both emerged in three-set outings, with Kalinskaya outlasting Elise Mertens 6-4 0-6 7-5, while Samsonova upset world number four Aryna Sabalenka 6-4 2-6 6-2.

World number 12 Veronika Kudermetova kept her WTA Finals hopes alive with a 6-4 7-5 win over Donna Vekic, and the Czech Republic's Marie Bouzkova ousted Colombia's Camila Osorio 6-3 6-1.

In the late window, Sloane Stephens eliminated Olympic gold medalist Belinda Bencic 6-4 6-4, and top overall seed Paula Badosa retired due to injury after losing the first set 6-2 against Victoria Azarenka.

The top seed in action on Tuesday at the Guadalajara Open made it through her opening match unscathed as Maria Sakkari defeated Marta Kostyuk 6-4 6-4.

Sakkari is one of the players needing a strong result in the tournament to break into the top-eight of the world rankings to qualify for the upcoming WTA Finals, entering the week at 10th, but only needing to make up one spot, with number eight Simona Halep out due to injury.

With her victory over Kostyuk, Sakkari avoided notching four consecutive losses for the first time this season, and will likely only need one more win to move into WTA Finals contention.

Her next opponent appears to be world number 16 Danielle Collins, who had no issue dispatching American compatriot Caroline Dolehide 6-4 6-1 to book her second-round fixture against Magdalena Frech after the Polish qualifier beat Yulia Putintseva 6-3 6-4.

World number seven Daria Kasatkina also should be locked into the WTA Finals after cruising past China's Lin Zhu 6-1 6-2, while 18th-ranked Beatriz Haddad Maia's season is over after a disappointing 7-5 6-2 upset loss to Katerina Siniakova.

Petra Kvitova needed to reach the final to have a chance of qualifying, but after a strong first set she fell 3-6 6-2 6-0 against Canada's Bianca Andreescu. In a good day for the Canadians, Eugenie Bouchard also beat Kayla Day 7-5 6-3 as the former world number five fights her way back up the rankings after a long injury layoff.

Italy's Elisabetta Cocciaretto defeated Russia's Anastasia Potapova 6-2 6-1, while Latvia's top talent Jelena Ostapenko cruised past America's Lauren Davis 6-1 6-3.

Madison Keys was too strong for Magda Linette in a 6-3 6-3 triumph, and in an all-Czech matchup, Marie Bouzkova downed Tereza Martincova 6-2 7-5.

Croatia's Donna Vekic eliminated Brazil's Laura Pigossi 6-4 6-1, and Italy's Martina Trevisan showed why she is top-30 in the world with a convincing 6-4 6-3 straight sets win against Japan's Nao Hibino.

In the last match of the night, world number 10 Caroline Garcia survived an early scared to come from behind and defeat Rebecca Marino 6-7 (2-7) 6-3 7-6 (7-5).

World number one Iga Swiatek claimed her eighth WTA Tour title of the season, storming home to claim a three-set victory over Donna Vekic in the San Diego Open final on Sunday.

Swiatek improved her record in the United States to 24-1 this season with the victory in one hour and 47 minutes, getting past the Croatian qualifier 6-3 3-6 6-0.

The Pole previously won the US Open, along with the Indian Wells and Miami titles this season.

Top seed Swiatek secured her 64th win of the season, which is the most since Serena Williams won 78 in 2013.

Vekic ensured it was not easy for Swiatek, continuing her excellent week – knocking out Maria Sakkari, Karolina Pliskova, Aryna Sabalenka and Danielle Collins - with a strong second set.

The Croatian actually had to complete her semi-final earlier on Sunday after a rain-interrupted encounter with Collins, winning 6-4 4-6 7-6 (7-2) after resuming 4-2 down in the third set, before taking on Swiatek.

Swiatek's dominance was felt, winning 82 per cent of her second-serve points, ruthlessly converting four of six break points as well.

Vekic only generated one break point for the match but she took it, keeping the match alive in the second set where she was more aggressive.

The 2022 US Open and French Open champion responded emphatically in the final frame, capitalising on three of four break points and winning 24 of the 29 points for the set to triumph.

World number one Iga Swiatek qualified for her ninth WTA Tour of the year, coming from a set down to get past fourth seed Jessica Pegula at the San Diego Open on a rain-affected Saturday.

Swiatek was at her dominant best against Pegula after dropping the opening frame, breaking her opponents' serve four times in the latter two sets to triumph 4-6 6-2 6-2 in two hours and six minutes.

The Pole extended her domination of Pegula this year, winning all four of their encounters in 2022, while the victory is her 63rd of the season, equaling Angelique Kerber's mark from 2016. Swiatek is also 23-1 in the United States this season.

Swiatek finished with 22-8 forehand winners, while she won 75 per cent of her second serves, compared to Pegula's 38 per cent.

After Pegula won the first set that included three breaks of serve, the match was halted for more than an hour due to rain, with Swiatek revealing post-game she passed time with crosswords.

That worked for the top seed who raced to a 3-0 second-set lead after the resumption and did not drop serve for the remainder of the match, saving three break points at 2-2 in the third.

The 2022 French Open and US Open champion will take on either Croatian qualifier Donna Vekic or American world number 19 Danielle Collins in Sunday's decider after their semi-final was ultimately suspended due to rain.

Collins leads Vekic 4-6 6-4 4-2 with the match restarted three times after rain, before the call was made to postpone it until Sunday, no earlier than 12.30pm local time, with the final to be played later in the day.

World number one Iga Swiatek thrashed Coco Gauff to clinch a third straight WTA Tour semi-finals berth after moving into the San Diego Open final four on Friday.

Swiatek was irrepressible against the 18-year-old American, extending her head-to-head dominance to 4-0 with a 6-0 6-3 victory in 66 minutes.

The Pole won the first eight games of the match and always appeared in control with her reliable forehand a key feature.

Swiatek laced 13 winners with only nine unforced errors, breaking Gauff five times. The American committed 26 unforced errors for the match.

The victory is Swiatek's 62nd of the season, moving her closer to Angelique Kerber's 2016 mark of 63.

Swiatek will face fourth seed Jessica Pegula in the semi-finals as the Pole aims for her eighth WTA title of the season.

Pegula secured her berth in the final four with a 6-4 7-5 victory over compatriot Madison Keys in their first-ever meeting in one hour and 34 minutes.

Third seed Aryna Sabalenka was a surprise casualty as Croatian qualifier Donna Vekic continued her excellent week with a 6-4 6-7 (5-7) 6-1 in two hours and 37 minutes.

World number 77 Vekic has beaten former world number three Maria Sakkari and two-time major finalist Karolina Pliskova this week.

Second seed Paula Badosa was also bundled out by American Danielle Collins 7-6 (7-5) 6-4. Collins will meet Vekic in the last four.

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.

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.

Naomi Osaka suffered another early major exit at the US Open on Tuesday and reflected on a difficult season.

Osaka is a four-time grand slam champion, winning twice at Flushing Meadows in 2018 and 2020.

However, the former world number one has not been able to contend in 2022, winning only two matches at majors – both at the Australian Open.

In fact, Osaka has not been beyond the third round at a slam since her most recent title in Melbourne at the start of 2021.

Tuesday's 7-6 (7-5) 6-3 defeat to Danielle Collins was just the 22nd Tour-level match Osaka has played this year.

"This year hasn't really been a great year," she said, adding: "I feel like everyone deals with injuries. I would say, for me, it's been more prominent this year.

"But I think it's something that I can learn [from]. I learned a lot more about my body, I learned what's weak, what I can do to prevent it.

"I would say the sport is definitely very physical, but it's my job to stay on top of it."

Given her fitness troubles, Osaka was just relieved to be able to play a competitive match against Collins, even if it was a fourth defeat in a row – her worst run since 2018.

"Honestly, the main goal was just to have fun," she said. "I don't know. I think that was kind of accomplished.

"Of course, it's more fun to win more rounds. We're just kind of winging it."

Naomi Osaka's difficult run of form continued in the opening round of the US Open on Tuesday, going down against Danielle Collins 7-6 (7-5) 6-3 in the final match of the night.

Osaka was the unseeded party as she went up against the world number 19, but she appeared to have things clicking early as she collected an early break of serve to rattle off the first three games of the match.

But as would be a theme in the back-and-forth contest, Collins fought right back, taking the next three games to even things up.

Collins' serve was not sharp throughout the clash – committing all nine of the match's double faults – but she found a couple of crucial first serves in the tiebreaker to come away with the first set.

Just like the first set, it was Osaka nabbing the early break in the second, but that advantage was again wiped out instantly as Collins fought back to level, before breaking again to go up 5-3 with a chance to serve it out.

Osaka had two break points in the final game, but could not extend the contest as Collins saved five out of six break opportunities in the second set, while taking two of her three chances.

Data Slam: Osaka's yearly grand slam streak comes to an end

This will be the first year since 2017 that Osaka has not won a grand slam, after her two Australian Open victories in 2019 and 2021 and two US Open crowns in 2018 and 2020.

She has now lost four matches in a row for the first time since 2018, and six of her past seven.

WINNERS/UNFORCED ERRORS

Osaka – 25/19

Collins – 23/24

ACES/DOUBLE FAULTS

Osaka – 8/0

Collins – 1/9

BREAK POINTS WON

Osaka – 2/8

Collins – 3/5

Top seed Danielle Collins suffered a shock defeat in a marathon first-round match with Simona Waltert at the Ladies Open Lausanne.

Collins, ranked a career-high seventh in the world, lost to a player 147 places below her as home hope Waltert prevailed in a final set tie-break.

The American battled back from a break down three times in the final set and had three match points in the tie-break.

But Collins could not find the telling blow as Waltert improbably turned the tide to win five successive points, and claim her first top-10 win 6-7 (5-7) 6-3 7-6 (8-6) after three hours and one minute of play.

Meanwhile, Waltert's compatriot Belinda Bencic survived a scare to avoid joining Collins on the casualty list, recovering from a set down to beat Diane Parry 3-6 6-3 6-1.

World number 77 Parry has claimed notable recent scalps in former French Open champion Barbora Krejcikova at Roland Garros and Kaia Kanepi at Wimbledon, but was denied another as the second seed hit back to advance. 

But there was no joy for fifth seed Nuria Parrizas-Diaz, who suffered defeat to Petra Martic, while eighth seed Varvara Gracheva lost to qualifier Eva Lys.

However, third seed Irina-Camelia Begu overcame Tamara Korpatsch in straight sets and sixth seed Caroline Garcia - fresh off a fourth-round run at Wimbledon - defeated Jasmine Paolini 6-3 6-3.

At the Hungarian Grand Prix, second seed Martina Trevisan came from a set down to survive against Natalia Szabanin and third seed Yulia Putintseva and ninth seed Anna Bondar also prevailed.

World number one Iga Swiatek beat Victoria Azarenka 6-4 6-1 to progress to the quarter-finals of the Internazionali d'Italia in Rome on Thursday. 

Swiatek, who became the first female player to win 25 consecutive matches since Serena Williams in 2015, will face Bianca Andreescu in the last eight after she eased past Petra Martic 6-4 6-4.

"I didn't start well, and everybody could see that," Swiatek told reporters. "I'm really happy with the way I reacted and how I improved in the first set.

"Also how different the second set looked to the first one because I could really reset and really change the way I played. That's the most positive thing for me."

There was a shock in the final game of the day, though, as Daria Kasatkina dumped out number two seed Paula Badosa 6-4 6-4. 

Third seed Aryna Sabalenka sealed a third straight win over Jessica Pegula, easing to a 6-1 6-4 victory, while fourth seed Maria Sakkari defeated Coco Gauff 6-4 7-5.

Seventh seed Danielle Collins was knocked out by unseeded compatriot Amanda Anisimova, the 20-year-old cruising past the Australian Open finalist 6-2 6-2.

There were also victories for Jil Teichmann, who overcame Elena Rybakina 6-7 (3-7) 6-3 7-5, and ninth seed Ons Jabeur, who beat Yulia Putintseva 6-3 6-2.

Naomi Osaka joined several other big names in falling to a second-round exit at the Madrid Open, although Emma Raducanu cruised to a routine straight-sets win over Marta Kostyuk.

Four-time grand slam winner Osaka crashed to a resounding 6-3 6-1 loss to Spain's Sara Sorribes Tormo, exiting her first tournament on clay since the 2021 French Open, where she withdrew citing mental health issues.

Osaka, who had posted an underwhelming 20-15 record on the surface prior to this week, looked uncomfortable throughout and appeared to struggle with a leg injury during a disappointing second set display.

The 24-year-old was not the only high profile player to be on the receiving end of a shock during a day of drama in the Spanish capital, as several of the competition's seeds failed to secure places in the last 16.

Another home favourite, Garbine Muguruza, fell to a resounding loss of her own as Anhelina Kalinina raced to a 6-3 6-0 victory over the seventh seed, while sixth seed Danielle Collins was thrashed 6-1 6-1 by Canadian Bianca Andreescu.

Fourth seed Maria Sakkari was the highest-ranked player in action, and although the world number five won the first set of her clash with Daria Kasatkina, the Greek eventually fell to a 3-6 6-3 6-1 loss, while 2021 US Open runner-up Leylah Fernandez went down 6-4 6-4 to Jil Teichmann.

One big name who did make comfortable progress, however, was Fernandez's US Open conqueror Raducanu, who eased to a 6-2 6-1 win over Kostyuk to set up a last-16 encounter with another Ukrainian in Kalinina. 

The 19-year-old, who has been quoted as saying she believes clay could prove to be her best surface in the future, was delighted with her victory and enjoying the tournament after dropping just one game in the second set.

"I'm definitely happy with my performance," Raducanu said on court. "Marta's a great opponent - I knew it was going to be a really tough battle. I went out there trying to be really aggressive and it paid off.

"It's my first clay court season and I'm really enjoying it. Madrid is such a cool city and it's got such a great vibe about it. I definitely want to try and stay here for as long as possible."

Naomi Osaka will make her first Miami Open semi-final appearance after defeating Danielle Collins 6-2 6-1 on Tuesday.

The Florida native and the 2022 Australian Open finalist were worlds apart on serve, with Osaka putting up 13 aces, while Collins served seven double faults and had a meagre first-serve rate of 37.8 per cent.

While dropping only three games provides ample reflection, Osaka was in almost total control, winning 28 of 38 total points on serve and over half of the points on return with 26 out of 45. Her 25 winners to three unforced errors only reinforced the dominant nature of the win.

The Japanese former world number one has not dropped a set en route to the semi-final, and did not face a single break point against Collins, who called a medical time-out to address a neck issue after the first set.

"I'm glad I was able to get through quickly," Osaka said post-match. "I focused on trying to hit a lot of really good returns.

"This is actually my first night match too, so I didn't know what the conditions were going to be like."

Osaka will face reigning Olympic champion Belinda Bencic, who comfortably saw her way past Daria Saville with a 6-1 6-2 win.

The Tokyo gold medallist progressed to her first WTA 1000 semi-final since Madrid in 2019, needing just 69 minutes to defeat the unseeded Australian.

With Saville serving at 51 per cent for the match, Bencic was all over the second look, winning 18 of a total 23 points in those scenarios.

The critical element of the match was the Swiss 22nd seed's ruthlessness on break point, converting seven out of total eight times.

World number two Iga Swiatek showed why she is next in line to occupy the top ranking as she comfortably handled the challenge of 14 seed Cori Gauff 6-3 6-1 to earn a spot in the quarter-finals at the Miami Open.

Swiatek, 20, will become the first Polish-born man or woman to earn the number one singles ranking when it is next updated on April 4, after Ash Barty's retirement, and she never gave Gauff a chance.

She won all eight of her service games in the match, and broke Gauff's serve four times in eight chances to rattle off five consecutive games to close the match.

After a walkover in her last fixture, Naomi Osaka was strong on her way to a 6-3 6-4 win against Alison Riske.

Both women produced break points throughout the match, but while Osaka saved seven out of eight, coming back to double-break after her slip-up in the second set, Riske could only save nine of 12.

In a clash between top-10 seeds, Danielle Collins was terrific in her 6-2 6-4 win against Ons Jabeur.

The match was decided by each woman's success on their second serve, as Jabeur had the better first serve, but could only win 31 per cent of her second serves (8-26), while Collins was an even 73 per cent on both her first and second attempts.

Daria Saville continued her march back up the rankings with a 5-7 6-4 7-5 win against Lucia Bronzetti, making it nine wins from her past 10 matches for the Australian ranked 249 in the world after recently returning from a long-term achilles injury.

Saville will play Switzerland's Belinda Bencic after she breezed past Belarus' Aliaksandra Sasnovich 6-2 6-3, while Petra Kvitova got the better of higher-ranked Veronika Kudermetova 7-6 (7-5) 6-4.

American Jessica Pegula was nearly flawless on her way to a 6-0 first set before Ukrainian Anhelina Kalinina retired due to injury, while world number six Paula Badosa beat wildcard Linda Fruhvirtova 6-2 6-3.