Emma Raducanu triumphed in a battle of US Open champions as she started her Australian Open campaign with victory over Sloane Stephens.

The 19-year-old stunned the tennis world when she claimed the title at Flushing Meadows last year after progressing all the way through the qualifying rounds and main draw without dropping a set.

The Briton struggled to build on those famous two weeks in New York, losing four of her next six matches including a 0-6 1-6 thrashing by Elena Rybakina at this month's Sydney Tennis Classic.

However, she put that result firmly behind her with an impressive 6-0 2-6 6-1 defeat of Stephens in her first match in the main draw of the Melbourne grand slam.

The first set was in keeping with Raducanu's US Open performance as she clinched it in just 17 minutes while dropping only four points.

But American Stephens, champion in her home slam in 2017, fought back in the second set and set up a decider with a forehand winner.

Yet the 17th seed responded well, marching into a 5-0 lead before serving out the match to set up a second-round clash with Danka Kovinic.

"I think both me and Sloane really put everything out there and gave it everything we had," she said.

"I think it was a really high-quality match, with some very long rallies. I'm very happy to come through against a great champion like her."

France's Billie Jean King Cup defence ended at the hands of the Russian Tennis Federation, who will meet the United States in the semi-finals after Wednesday's play in Prague. 

Clara Burel put France on course for the 3-0 victory they needed to advance from Group A with a three-set victory over Ekaterina Alexandrova, but Anastasia Pavlyuchenkova outlasted Alize Cornet in the second rubber to ensure a new champion will be crowned. 

Pavlyuchenkova saved six of 10 break points and racked up an impressive 34 winners en route to a crucial 5-7 6-4 6-2 success against Cornet. 

"I'm so, so happy and so proud of myself because I think it was an incredible match. It was very good tennis but more importantly I think it was an amazing fighting spirit from both of us," said Pavlyuchenkova. 

"We were like two tigers. Nobody wanted to give the other anything and I think that's what matters. That's the sport we're playing." 

Veronika Kudermetova and Liudmila Samsonova comfortably defeated Cornet and Burel in the doubles to consign the reigning champions to a 2-1 defeat. 

The RTF will go up against the USA in the first semi-final, with the Americans comfortably seeing off Spain in the singles rubbers. 

Sloane Stephens bested Nuria Parrizas-Diaz 6-4 6-4 before Danielle Collins swept Sara Sorribes Tormo aside 6-1 6-0 in under an hour. 

Collins won 83 per cent of points behind her first serve and forced Sorribes Tormo into 24 errors during a resounding victory. 

Spain avoided a 3-0 defeat, though, with Aliona Bolsova and Rebeka Masarova beating Caroline Dolehide and CoCo Vandeweghe 6-3 6-4 in the doubles rubber. 

Former US Open champion Sloane Stephens had to come from behind to progress against Heather Watson after almost three hours in the Indian Wells Open first round.

Stephens, who is currently ranked 73rd in the world, having been number three on the WTA Tour in 2018, triumphed 6-7 (5-7) 7-5 6-1 over Watson in two hours, 50 minutes on Wednesday.

In a see-sawing match, there were six breaks in the opening set, as Watson got the edge early on Stephens' serve at the WTA Premier 1000 event.

Stephens steadied by claiming a late break in the second to level the match, before dominating the third set.

Playing at her 10th Indian Wells Open, Stephens won seven consecutive games after the match was 5-5 in the second set.

"After the first set, that was disappointing to lose that one, but I felt like it was a battle and I was still in the match," Stephens said. "I knew I had to keep fighting and that's what I did, and I'm just really pleased to have squeaked out a win here."

KEYS ON SONG IN OPENER

Former world number seven Madison Keys moved through to the second round with a 6-0 7-5 win over fast-finishing Estonian veteran Kaia Kanepi.

American Keys won 21 consecutive points as part of a streak where she clinched the first nine games of the match, withstanding Kenapi's late push.

Keys will take on Russian ninth seed Anastasia Pavlyuchenkova for a spot in the third round.

SAMSONOVA, MARTIC, ROGERS AND PUTINTSEVA PROGRESS

Liudmila Samsonova, who made the fourth round at Wimbledon earlier this year, needed more than two hours to get past Ukrainian qualifier Kateryna Kozlova 6-4 7-6 (8-6).

Samsonova will face countrywoman and 25th seed Veronika Kudermetova in the second round.

Petra Martic won through to take on second seed Iga Swiatek with a 6-4 6-4 victory over American wildcard Katie Volynets.

Ash Barty's US Open conqueror Shelby Rogers claimed her 25th win for the year, getting past Ukrainian Anhelina Kalinina 7-6 (7-2) 6-2, while Yulia Putintseva won 7-6 (7-2) 6-1 over experienced German Andrea Petkovic to set up a showdown with fellow Kazakh player and 13th seed Elena Rybakina.

Sloane Stephens has detailed the online abuse she received after exiting the US Open to Angelique Kerber.

Stephens, who won at Flushing Meadows in 2017, was beaten 5-7 6-2 6-3 in the third round on Friday by three-time major champion Kerber.

The American had defeated outstanding teenager Coco Gauff in her previous match but could not maintain a title challenge in New York.

It was a defeat that prompted a shocking response on social media, Stephens revealed on Saturday.

"I am human," she wrote on her Instagram story. "After last night's match I got [more than 2,000] messages of abuse/anger from people upset by yesterday's result.

"It's so hard to read messages like these, but I'll post a few so you guys can see what it's like after a loss..."

Stephens then shared screenshots of a series of threatening, racist and misogynistic messages aimed in her direction.

She added: "This type of hate is so exhausting and never ending. This isn't talked about enough, but it really freaking sucks...

"I'm happy to have people in my corner who support me. I'm choosing positive vibes over negative ones.

"I choose to show you guys happiness on here, but it's not always smiles and roses."

Sloane Stephens sent Coco Gauff spinning out of the US Open – then joined the clamour to stop toilet break "gamesmanship" in tennis.

In Wednesday's opening night match on Arthur Ashe Stadium, former champion Stephens took the fast route past world number 23 Gauff, speeding to a 6-4 6-2 victory.

Now ranked 66th, Stephens won at Flushing Meadows in 2017 and was tipped by Gauff to challenge for the title again this year. By beating Madison Keys and now Gauff, Stephens is showing she still has major game, and another former champion in Angelique Kerber could be her third-round opponent.

Gauff, now 17, has known Stephens for over seven years, having attended the now 28-year-old's 21st birthday party.

But the American pair put friendship to one side for their showdown, with Gauff, who had been fancied by many to go deep this fortnight, having her threat stifled by an in-form Stephens.

"I think the last time we hit, she was probably like 12. It was a little bit different," Stephens said afterwards.

"It's just been really nice to see her game kind of evolve and the things that she's doing, like how she's able to turn so much defense into offense and kind of do those movements. She is great at the net. She has a really great all-around game. It's been really nice to see.

"She's different from a lot of the up-and-coming players we're seeing now that are just super hard hitting, not much variety. She has a lot of variety. I think a lot of the younger girls, there's half that are very hard hitting and half that have a lot of variety. I think she's in the bucket with a lot of variety."

Gauff was asked whether Stephens could now be considered a title contender and replied: "Yeah, definitely. Today she was playing well. I knew these last couple of tournaments she's been playing better and better. I hope that she can make it all the way to the end.

"Obviously if you are going to lose, you want to lose to the champion. I think that I feel like I've learned that I'm capable of making it far in slams. I think if I tighten up a few things, that I'm capable of winning one."

The debate over toilet breaks in tennis was sparked by Andy Murray being furious with Stefanos Tsitsipas for spending eight minutes in the bathroom before tackling the Scot in the deciding set of their first-round match.

Murray, frustrated to be left waiting for his opponent to reappear, followed up his Monday night fury with a tweet that charged Tsitsipas with taking twice as long to visit the toilet as Amazon mogul Jeff Bezos took to travel into space.

There was no such spat in Stephens' quickfire win over Gauff, but the rules on spending a penny have been the currency of many a news conference this week.

"I honestly just thought Andy's tweet was really funny," said Stephens. "I didn't see exactly what happened. I'm not sure. I just thought it was hilarious. We all are like huge Andy fans. We love him.

"I can't speak for what happened in that match, but I do know on the girl's side, there still is a lot of that. It's gamesmanship.

"I think there definitely needs to be a rule or changes. They make a lot of rule changes for smaller things, like they took one minute off the warm-up. If someone goes to the bathroom for nine minutes, no one says anything.

"Six, eight minutes is a long time to leave a match. That changes the whole momentum of a match. If you're changing your clothes, what are you changing? What are you doing in there?

"When you get into six, seven, eight, nine minutes, okay, what are you doing in there? Do you need help? I can come help you. Like, what's happening? I think that's more where the issues are because it just becomes pure gamesmanship."

Stefanos Tsitsipas has defended his "personal need" for long bathroom breaks after being jeered during his four-set second round win over Adrian Mannarino at the US Open on Wednesday.

The world number three triumphed 6-3 6-4 6-7 (4-7) 6-0 but was booed by the Arthur Ashe Stadium crowd after taking a bathroom break which exceeded seven minutes.

The Greek was criticized by Andy Murray, who said he lost respect for Tsitsipas after taking a lengthy break ahead of the final set in their five-set first round epic on Monday.

Alexander Zverev weighed in on the discussion, claiming Tsitsipas was communicating with his coach during his bathroom breaks, labelling them "ridiculous" and saying he had broken an "unwritten law".

Tsitsipas reverted to the rule book in his defence after beating Mannarino, insisting he had done nothing illegal and longer breaks were part of his "personal needs".

"It's just my personal needs," Tsitsipas told reporters. "Some people have other needs. Some people take much more than 25 seconds between points, which is fair.  

"I've done everything the right way. If I haven't I should be penalized. I completely agree with it. I should get a fine or be penalized if I haven’t followed whatever I've done correctly. But as far as I know, it is a necessity, it is a need when I'm out there playing and performing."

Tsitsipas said he felt fans who booed and jeered did not understand the game or his need to take longer bathroom breaks.

"I haven’t done anything wrong so I don't understand," he said. "The people love the sport, they come to watch tennis. I have nothing against them. But some people don't understand. They haven't played tennis at high level to understand how much effort and how much difficult it is to do what we are doing."

He added: "It is important. First of all, you carry less weight on you with all the sweat. You feel rejuvenated, you feel fresh, and you don't have all the sweat bothering you and coming in your face, on your fingers, everywhere all over your body. It makes you feel better.

"For me it is important to take that break. For someone else probably not. And everyone has his own time. I try and be as quick as I can. Sometimes I just need a bit more time."

Tsitsipas added that he was taken aback by the public criticism from Murray and Zverev.

"I never complain of what other players do," the 23-year-old French Open runner-up said. "My parents have taught me not to watch other people's business and concentrate on myself. Do my job.

"I just don’t understand when some players go and criticize other players, or during a match they put too much emphasis on it."

There have been calls for a hard cap on the permitted time for bathroom breaks, which American Sloane Stephens agreed with, speaking after her straight-sets win over 21st seed Coco Cauff.

"I don't think you should be gone from the court for six-eight minutes," Stephens said. "It's a long time to leave a match. That changes the whole momentum of a match.

"I can't speak for what happened in that match, but I do know on the girls' side, there still is a lot of that. It's gamesmanship.

"I think there definitely needs to be a rule or changes. They make a lot of rule changes for smaller things, like they took one minute off the warmup. If someone goes to the bathroom for nine minutes, no one says anything."

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. 

Top-seeded Elise Mertens pulled out a three-set win to reach the quarter-finals at the Silicon Valley Classic as all four matches went the distance on Thursday.

The Belgian, ranked 17th in the world, prevailed 6-2 4-6 6-4 over Kristina Mladenovic of France in two hours and 40 minutes to advance in San Jose.

She moves on to face the eighth seed, Yulia Putintseva, who rallied past Ajla Tomljanovic 3-6 7-5 6-3 as the Australian blew numerous chances to pull ahead by converting only two of 16 break-point opportunities.

In the bottom half of the draw, second seed Elena Rybakina remained on track with a 2-6 6-0 6-2 victory over American Claire Liu in a rematch of a second-round meeting at Wimbledon.

Rybakina next meets seventh seed Danielle Collins, a 3-6 6-4 6-3 winner over US countrywoman Sloane Stephens.

Stephens, the 2017 US Open champion, has slipped to number 67 in the world and was playing in her first tournament since Wimbledon as she prepares for a return to Flushing Meadows.

Novak Djokovic will start the defence of his Wimbledon title against British wildcard Jack Draper, and Serena Williams takes on Aliaksandra Sasnovich in the first round.

Djokovic is just one grand slam title away from matching Roger Federer and Rafael Nadal's record tally of 20 after winning the Australian Open and French Open this year.

The world number one will take on 19-year-old Draper, a quarter-finalist at Queen's Club last week, in his first match at SW19 for two years after the 2020 championships were called off due to the coronavirus pandemic.

Djokovic faces a potential quarter-final against Andrey Rublev, while Federer could come up against second seed Daniil Medvedev in last eight.

First up for eight-time Wimbledon champion Federer is an encounter with Adrian Mannarino, while injury-plagued two-time winner Andy Murray will start his home major against the 24th seed Nikoloz Basilashvili.

Stefanos Tsitsipas, beaten by Djokovic in a thrilling French Open final this month, has been drawn to face American Frances Tiafoe in round one of a tournament that gets under way on Monday.

Simona Halep announced just before the draw was made on Friday that she would not defend her title due to a calf injury.

Williams, runner-up to Halep in the 2019 final, must get past Sasnovich of Belarus in the first round and could face third seed Elina Svitolina at the quarter-final stage.

World number one and top seed Ash Barty takes on Carla Suarez Navarro, who made a grand slam return at Roland Garros after recovering from cancer. Barty could come up against Bianca Andreescu in the last eight.

Petra Kvitova against Sloane Stephens is a standout first-round match, while Coco Gauff's first assignment will be a meeting with 20-year-old Briton Fran Jones.

Petra Kvitova came from a set down to beat Katarzyna Piter on her return from injury at the Bad Homburg Open, while no play was possible in Eastbourne on Monday due to rain.

Kvitova withdrew from the French Open after suffering a freak ankle injury during her post-match media duties at Roland Garros.

The two-time Wimbledon champion recovered to get her grass-court season under way in Germany and battled to a 4-6 6-1 6-4 over Polish outsider Piter.

A week before the third grand slam of the year gets started at the All England Club, top seed Kvitova trailed 2-0 in the final set as she struggled with her serve, but broke three times to book a second-round meeting with Ann Li.

Sloane Stephens withdrew ahead of her scheduled match with Laura Siegemund due to a foot injury. Riya Bhatia stepped in with Stephens absent, but Siegemund consigned her to a 2-6 7-6 (7-1) 6-1 defeat.

Angelique Kerber needed only 50 minutes to see the back of Ekaterina Yashina 6-1 6-1 on home soil, grasping all five break-point opportunities.

Kerber will do battle with Anna Blinkova in round two and Jessie Pegula's next assignment is an encounter with Katerina Siniakova following a 6-1 6-2 defeat of Amandine Hesse.

Blinkova beat Clara Tauson 7-6 (7-4) 4-6 6-2, while Sara Sorribes Tormo saw off Martina Trevisan 6-4 3-6 6-2

Miserable weather in Eastbourne prevented Karolina Pliskova, Madison Keys, Bianca Andreescu and Madison Keys from playing at the Viking International.

Ashleigh Barty described her retirement from Thursday's second-round clash against Magda Linette at the French Open as "heartbreaking". 

Top seed Barty required medical attention during her first-round win over Bernarda Pera two days earlier, with a hip injury the cause for concern.

The 25-year-old – back at Roland Garros for the first time since winning her maiden grand slam title in Paris in 2019 – vowed to "play through the pain barrier", yet the injury prevented her from continuing when 1-6 2-2 down against her Polish opponent, who will face Ons Jabeur in the next round. 

The Australian's retirement throws the draw wide open, with both of the top seeds now out after Naomi Osaka decided to withdraw amid her disagreement with tournament organisers.

Barty's clay-court season ended with a title in Stuttgart, a runner-up finish in Madrid and an appearance in the quarter-finals in Rome, and she could scarcely hide her disappointment at the way things ended for her in the French capital. 

"It's heartbreaking," she told a media conference. "I mean, we have had such a brilliant clay-court season, and to get a little bit unlucky with timing and have something acute happen over the weekend and just kind of run out of time against the clock is disappointing. 

"It won't take away the brilliant three months that we have had, as much as it hurts right now.

"We did everything, absolutely everything we could to give myself a chance. It was a small miracle that we were able to get on court for that first round.

"I just tried to give myself a chance and see how it felt. Obviously practicing, we've had our restrictions and essentially tried to stay as fresh as possible and not aggravate it in any way, but in a match that's unavoidable at times.

"It got worse today and it was becoming at the stage where it was unsafe. As hard as it is, it had to be done. Right from the first game, I was battling the pain, and it just became too severe."

SVITOLINA CRUISES THROUGH, PLISKOVA DUMPED OUT

Fifth seed Elina Svitolina booked a third-round meeting with Barbora Krejcikova after seeing off Ann Li 6-0 6-4. 

Svitolina landed 74 per cent of her first serves and struck 10 winners to cruise past the American in the opening set. 

Li bounced back in the second, roaring into a 4-1 lead, but Svitolina clawed her way back to ensure she reached at least the third round in seven of her nine appearances at Roland Garros. 

Svitolina, who overturned a 2-5 deficit in the second set to beat Oceane Babel in the first round, said: "In the end, what I'm really happy with is the way that I was down in both matches in the second set and found a way. 

"I found a good level and didn't give up on the second set. That was a really good point for me, and I was really playing composed in both matches. It was two different players, but I was really happy that I could win in two sets in both matches."

Up next is Krejcikova, who overcame Ekaterina Alexandrova 6-2 6-3.

There is no place in the third round for ninth seed Karolina Pliskova, who was soundly beaten 7-5 6-1 by Sloane Stephens, while number 13 seed Jennifer Brady battled past Fiona Ferro 6-1 1-6 6-4. 

KENIN WINS BATTLE OF THE AMERICANS

Fourth seed Sofia Kenin defeated fellow American Hailey Baptiste, a qualifier who won four matches in Paris on her French Open debut, 7-5 6-3. 

Kenin will now face another compatriot in 28th seed Jessica Pegula, who beat Tereza Martincova 6-3 6-3.

Elsewhere, defending champion Iga Swiatek thumped Rebecca Peterson 6-1 6-1, Coco Gauff got the better of Wang Qiang 6-3 7-6 (7-1), and Elise Mertens edged out Zarina Diyas 6-4 2-6 6-4.

Coco Gauff battled through to the second WTA final of her burgeoning career as the 17-year-old American sank the title hopes of Katerina Siniakova in Parma.

At the Emilia-Romagna Open, Gauff scored a 7-5 1-6 6-2 victory over the player who shocked top seed Serena Williams in round two of the clay-court tournament.

It means Gauff faces a first final appearance since landing the Linz Open title as a 15-year-old in October 2019, with Wang Qiang awaiting her in the title match after a dramatic win over former US Open champion Sloane Stephens.

Gauff served eight double faults against Siniakova, a familiar weakness in her game, but her opponent was similarly afflicted and coughed up 10 doubles across the two hours and eight minutes of their contest.

Having reached the semi-finals of the WTA 1000 event in Rome last week, Gauff is enjoying her stay in Italy ahead of competing at the French Open.

"I need to play more aggressive. I learned to trust my shots and they ended up working out," she said on Amazon Prime. "The Italians, they cheer me on and bring me good luck, and hopefully I can keep this going tomorrow."

Wang beat Stephens 6-2 7-6 (7-3), but the scoreline barely told the story of the second semi-final. It seemed sure to go to a third set as Stephens raced to a 5-1 lead in the second, but Wang reeled her in before easing through the tie-break.

Chinese star Wang, coached by former Wimbledon champion Pat Cash, said: "I just tried to hang in there and focus on the court, try to hit every ball back. It will be my first time to play [Gauff] and I will make a plan tonight."

At the Serbia Open, promising Colombian teenager Maria Camila Osorio Serrano set up a semi-final against Croatian Ana Konjuh by beating world number 50 Aliaksandra Sasnovich.

Osorio Serrano secured a 6-4 6-2 success, while Konjuh saw off Argentinian Nadia Podoroska 6-4 6-3. In the top half of the quarter-final draw, Spain's Paula Badosa was a 6-2 6-4 victor over Swedish player Rebecca Peterson, and Bulgarian Viktoriya Tomova edged out Hungarian Reka-Luca Jani 6-1 2-6 7-5.

Coco Gauff continued her fine form with a 6-3 6-3 quarter-final triumph over fellow American Amanda Anisimova at the Emilia-Romagna Open.

In a contest between two teenage stars, it was 17-year-old Gauff who sealed her second semi-final spot in as many weeks, having made the last four at the Internazionali d'Italia.

Third seed Gauff will face Katerina Siniakova next, after the Czech followed up her win over Serena Williams with a 7-5 6-1 defeat of Caroline Garcia.

"I was pretty satisfied with the way I played," Gauff said, after fending off Anisimova.

"I do think I could have served a little bit better, but other than that, I was pretty happy with the way I played."

Despite her valid concerns, Gauff won 72 per cent of points after landing her first serve and forced six breaks to win in style, reeling off six games on the trot from 3-0 behind in the second set.

The other semi-final will see second seed Wang Qiang take on Sloane Stephens.

Wang prevailed 7-6 (7-4) 3-6 7-5 against Petra Martic, while Stephens saw off Sara Errani 6-3 6-0.

It was another rain-affected day at the Serbia Open, where Maria Camila Osorio Serrano managed to get past Kamilla Rakhimova 4-6 6-3 6-4.

Anna Kalinskaya and Reka Luca Jani were locked at one set apiece in the only other match to get started before the weather halted play.

Serena Williams saw her hopes of an extended run at the Emilia-Romagna Open come to an early end on Tuesday, the top seed succumbing to Katerina Siniakova in straight sets.

Williams had taken up a wildcard to play in the tournament following an early exit in Rome, where she was beaten by Nadia Podoroska in her opening contest in the clay-court swing.

Her campaign in Parma got off to a better start on Monday, a 6-3 6-2 result against WTA Tour debutant Lisa Pigato bringing a first triumph since losing in the semi-finals of the Australian Open in February.

However, the 23-time grand slam champion was unable to repel a determined Siniakova as she slipped out at the last-16 stage.

"It was a fantastic match and I played so well, I'm so happy that I could finish like that," Siniakova said after recording a 7-6 (7-4) 6-2 result.

"It was a pleasure to share the court with her.

"Now I will have the pressure because I defeated a great player, but I will enjoy it. I'm happy that I can continue and I will try to play my best in the next match."

Having failed to convert a set point opportunity, Williams hit back after losing serve with a break of her own to force a tie-break in the opener.

But Siniakova forced her way into a 5-3 lead before sealing it with a service winner, then quickly seized control of proceedings in a second set which was far less competitive.

Third seed Coco Gauff came through two tie-breaks to see off Kaia Kanepi, the American teenager having let slip a 5-1 lead in the second set before eventually sealing a 7-6 (8-6) 7-6 (9-7) win.

Petra Martic had no such issues in her opening contest against Varvara Gracheva, the second seed easing through 6-4 6-2 after one hour and 21 minutes on court.

Serena Williams had no problems in her opening match at the Emilia-Romagna Open, but sister Venus was unable to join her in the last 16.

Top seed Serena eased to a 6-3 6-2 triumph over teenage qualifier Lisa Pigato in the highlight of Monday's action in the clay-court tournament, wrapping up the result in 68 minutes.

Pigato, 17, was making her debut in the main draw of a professional event having come through qualifying in Parma.

She enjoyed early success against the legendary Williams, too, claiming a break of serve in the opening game, but the 23-time grand slam champion soon got to grips with the task at hand.

"The first game, she played really good and I needed to adjust to get back," Serena said afterwards. "It was a bit of both, figuring out her game as well."

Next up for the American, who accepted a wildcard into the event after an early exit at the Internazionali BNL d'Italia in Rome last week, will be Katerina Siniakova, a 6-1 6-3 winner over Clara Tauson.

Venus, however, failed to make it beyond her opening outing, losing out to Anna Karolina Schmiedlova despite taking the opening set.

The Slovakian made it four wins in five meetings against the seven-time major champion, eventually prevailing 5-7 6-2 6-2 after two hours and 39 minutes on court.

Elsewhere, Sloane Stephens defeated fellow American Caty McNally in two sets, while seventh seed Sara Sorribes Tormo overcame Bernarda Pera 6-4 6-2.

There was also a win in straight sets for eighth seed Caroline Garcia, who got the better of Paula Ormaechea in a contest that saw both players serve impressively.