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

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

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

BARTY PRODUCES COMEBACK

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

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

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

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

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

HALEP REACHES MILESTONE

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

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

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

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

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

KERBER'S DOUBLE BAGEL

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

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

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

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

Vasek Pospisil launched a stunning tirade during his three-set defeat to American qualifier Mackenzie McDonald in the first round of the Miami Open on Wednesday.

The Canadian former world number 25 was docked a point for verbal abuse, subsequently conceding the first set, before a meltdown during the change of ends.

Pospisil used a profanity in reference to ATP chairman Andrea Gaudenzi when speaking to chair umpire Arnaud Gabas.

“[Gaudenzi was] screaming at me in a player meeting for trying to unite the players — for an hour and a half," Pospisil said to Gabas. "If you want to default me, I’ll gladly sue this whole organisation.”

He did fight back to win the second set but ultimately lost to McDonald 6-3 4-6 6-3.

Pospisil, who is nowadays ranked 67th, was joined among the first-round exits by last week's Mexican Open semi-finalist Dominik Koepfer, who went down 6-1 6-4 to wildcard Hugo Gaston as he claimed his first career Masters 1000 win.

Sam Querrey, ranked 63rd, also bowed out 6-3 6-4 to Lu Yen-hsun, who will meet world number two Daniil Medvedev in the second round.

YOUNGSTER BEATS VETERAN

Australian youngster Alexei Popyrin secured his maiden win at the Miami Open, knocking out the oldest player in the draw Feliciano Lopez 6-4 7-6 (7-4).

Popyrin, 21, claimed his first ATP Tour title last month in Singapore and backed that up with a strong display against the 39-year-old former top 20 Spaniard.

Recent Open 13 Marseille runner-up Pierre-Hugues Herbert got past Portugal's Pedro Sousa 6-1 6-3, while South Africa's Lloyd Harris defeated Emilio Nava 6-4 7-6 (9-7).

Frances Tiafoe won in the final match of Wednesday, coming from behind to beat Stefano Travaglia 5-7 6-4 6-2.

COMEBACK CAM

Brit Cameron Norrie produced a heroic final-set fightback to claim his spot in the second round, where he will face Grigor Dimitrov.

Norrie trailed 5-1 in the third set against Yoshihito Nishioka, before winning 6-1 3-6 7-5, winning the last six games to clinch victory.

The 56th-ranked Brit sent down eight aces in the victory, although he got the edge on return and converted seven of his 10 break points.

SECOND ROUND

Top seed Medvedev will face Lu on Thursday, while third seed Alexander Zverev will take on Finland's Emil Ruusuvuori.

Norrie will meet Dimitrov, while 11th seed Felix Auger-Aliassime faces Herbert and eighth seed David Goffin will take on James Duckworth.

Harris has a match-up against seventh seed Roberto Bautista Agut.

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

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

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

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

SLOANE FIGHTBACK

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

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

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

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

FORMER MAJOR WINNER GONE

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

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

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

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

SECOND-ROUND MATCH-UPS

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

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

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

Three-time champion Venus Williams was dumped out of the Miami Open on Monday in straight sets by Kazakhstan's Zarina Diyas. 

Diyas, ranked 89th in the world, had lost her only previous match against seven-time major winner Williams, but saw off the American 6-2 7-6 (12-10).

"I'm very happy with the win, it was very tough," Diyas said after her victory. "Venus, I looked up to her when I was little, she's such a legend. So for me, it's a really special win."

Elsewhere, Shelby Rogers overcame fellow American Madison Brengle 6-3 6-3 to set up a second-round clash with fifth seed Elina Svitolina.

"I'm really happy to get through that one, she's a really tricky player," Rogers said. "It's actually my first win at this site. The last time I was here, I was spectating, as an injured person! So I'm very happy to be here."

There were also wins for Magda Linette, Sorana Cirstea, Barbora Krejcikova and Kaia Kanepi, while Ajla Tomljanovic beat Anastasia Potapova to seal a clash against second seed Naomi Osaka in the next round.

Andy Murray will not feature at the Miami Open after withdrawing from the tournament because of a groin injury.

The former world number one and three-time grand slam champion has featured only twice on the ATP Tour this season, losing in the first round in Montpellier before going one better in Rotterdam, where he was beaten by Andrey Rublev.

He withdrew from this month's Dubai Tennis Championships to be with his wife as she gave birth to their fourth child.

And his return to action has been delayed again, with Murray missing out on a tournament he has won twice.

The 33-year-old beat Novak Djokovic in the 2009 final and defeated David Ferrer to lift the trophy four years later. He lost to Djokovic in the final in 2012 and 2015.

Murray holds a 28-9 record in Miami, where he had been given a wild card. His place in the draw will be filled by a qualifier or a lucky loser.

The Scot has not competed in a Masters 1000 event since 2016, the next event at that level on the calendar is next month's Monte Carlo Masters.

Juan Martin del Potro will undergo knee surgery for the fourth time but retains hope of playing at the Olympic Games in Tokyo.

Del Potro, who was a career-high world number three in August 2018 and still in the top 10 fewer than two years ago, has not appeared on the ATP Tour since withdrawing from the Queen's Club Championships in 2019.

The 2009 US Open champion had his first procedure after falling at the tournament in London and another followed in January 2020.

The third operation came last August as pain persisted, but the issue still has not been eradicated.

However, Del Potro said in an Instagram post on Monday that the death of his father earlier this year had motivated him to continue pursuing a return to the court.

The 32-year-old, who won bronze for Argentina at the 2012 Olympics and silver four years later, will go under the knife again in Chicago on Tuesday.

"We've tried conservative therapy but the pain is still there," he wrote.

"[Doctor Jorge Chahla] knows I want to play tennis again and be able to play the Olympics, so we agreed that surgery should be done as soon as possible.

"Of course, these last few weeks weren't easy for me. Everything's so hard since my father's passing.

"But also, I feel the strength he sends me from above. I had this day in which I woke up and called the doctor. I knew I had to try again.

"I hope I can overcome this painful situation. I won't stop trying. Of course, your messages and best wishes are always welcomed. Thanks for the love."

Canadian teenager Leylah Fernandez celebrated her maiden WTA Tour title after winning the Monterrey Open in straight sets.

Fernandez broke through with a comfortable 6-1 6-4 victory over qualifier Viktorija Golubic on Sunday.

Featuring in her second WTA final after losing last year's Mexican Open in Acapulco, the 18-year-old Fernandez ensured she got her hands on the trophy this time.

Fernandez did not drop a set throughout the WTA International tournament, easing past her Swiss opponent in one-and-a-half hours.

Daria Kasatkina claimed the fourth title of her career after Margarita Gasparyan retired in the second set of the St Petersburg Ladies Trophy final with a back injury.

Kasatkina, who becomes the first player to win two WTA tournaments in 2021 having claimed the Phillip Island Trophy last month, was leading 6-3 2-1 when Gasparyan pulled out.

Gasparyan initially took a medical timeout after losing her first two service games of the match to trail 4-1 before eventually retiring after dropping her serve early in the second set.

Kasatkina's triumph meant she became the first player to win both WTA 500 events on Russian soil, previously claiming the 2018 Moscow title at this level.

The former top-10 player has endured a dip in recent seasons but will be back in the top 50 on Monday, while wildcard Gasparyan's maiden WTA 500 final means she returns to the top 100.

Kasatkina dropped the opening set in her quarter-final and semi-final matches but then swept through the next two sets emphatically on each occasion.

"I'm proud of how I was able to manage the pressure," Kasatkina said, quoted on the WTA website. "I felt differently during this tournament and I'm really proud of that."

German star Alexander Zverev was too strong for top seed Stefanos Tsitsipas in the Mexican Open final, claiming the title in straight sets after a stunning turnaround.

In a battle of the top two seeds, Zverev reigned supreme 6-4 7-6 (7-3) for his 14th ATP crown in Saturday's Acapulco decider.

Last year's US Open finalist Zverev was runner-up at the ATP 500 tournament in 2019, beaten by Australian Nick Kyrgios in straight sets.

But Zverev went one step further this year, taking down two-time Australian Open semi-finalist Tsitsipas after two hours, 17 minutes.

Zverev, who was rocked during his semi-final win over countryman Dominik Koepfer on Friday – a 5.7 magnitude earthquake registered as broadcast cameras shook, did not drop a set throughout his title-winning run.

Greek star Tsitsipas made an impressive start, racing out to a 3-0 lead after breaking Zverev in the second game.

Zverev, though, hit back as he put the set back on serve in the seventh game before consolidating.

Another break saw Tsitsipas come unstuck – Zverev reeling off six consecutive games to claim the opening set in red-hot fashion.

Zverev and Tsitsipas went toe-to-toe in the second set, the pair exchanging breaks late as a tie-break eventually saw the former complete a dominant display.

Leylah Fernandez and Viktorija Golubic will go head-to-head in the Monterrey Open after progressing on Saturday.

Canadian teenager Fernandez reached her second career WTA Tour singles final thanks to a 7-5 7-5 win over seventh seed Sara Sorribes Tormo.

The 18-year-old Fernandez – whose first final came via last year's Mexican Open in Acapulco, where she lost – converted six of nine break points and hit 35 winners.

Standing in Fernandez's way is Switzerland player Golubic.

Golubic upstaged eighth seed Ann Li 6-2 6-4 to become the first qualifier to advance to the Monterrey Open final in the tournament's history.

The 28-year-old Golubic also reached the Lyon Open final two weeks ago – beaten by Clara Tauson.

Aslan Karatsev captured the first ATP Tour title of his career as the late-blossoming Russian triumphed in the final of the Dubai Tennis Championships.

At the age of 27, and with little warning, Karatsev has hurtled from obscurity before tennis went into lockdown 12 months ago to real prominence.

A 6-3 6-2 victory over South African Lloyd Harris on Saturday gave him a trophy for his efforts and he will enter the top 30 on Monday, having never had a double-digit ranking before this season.

Karatsev reached the Australian Open semi-finals last month, having had to win three qualifying rounds to make the main draw, and it took Novak Djokovic to stop that charge in Melbourne.

Now Vladikavkaz-born Karatsev is back in another winning routine, with Andrey Rublev, Jannik Sinner and Dan Evans having figured among his victims en route to the Dubai final.

The first-time champion said on Amazon Prime: "I am super happy. It was a tight match. [I was] really nervous. I want to congratulate my opponent for the final [run]. He did a great week. Every final is different, so I am happy that I won."

Karatsev had some promising results at Challenger Tour level last year but had never shown form on the main circuit until the start of 2021, and suddenly he looks a major force to be reckoned with.

He said of the rush of success: "You never know when it is coming. I did a good job with my team, with my coach and it has happened now."

Daria Kasatkina and Margarita Gasparyan fended off two of the great stalwarts of Russian tennis to set up a final showdown at the St Petersburg Ladies Trophy.

Kasatkina recovered from a slow start to overcome fourth seed and two-time grand slam winner Svetlana Kuznetsova, after Gasparyan saw off former Wimbledon and US Open runner-up Vera Zvonareva.

Zvonareva, 36, and Gasparyan, whose promising career has been disrupted by injury, were both allocated wildcard entries to the tournament and seized advantage to reach the last four.

Gasparyan, a 26-year-old whose single-handed backhand is an unusual sight in modern tennis, came through the clash with Zvonareva a 6-3 7-6 (11-9) winner to reach her first final at WTA 500 level.

The world number 126 will tackle former top-10 star Kasatkina for the title, after the 23-year-old Barcelona resident scored a remarkable 1-6 6-0 6-2 win over Kuznetsova in the second semi-final.

It was a flat Kasatkina who surrendered the opening set, but she then dashed off eight games in a row, levelling the match and surging to a 2-0 lead in the decider, knocking the stuffing out of 35-year-old Kuznetsova's challenge.

Kasatkina, a 23-year-old with more variety than most, had also dropped the first set 6-1 in her quarter-final win over second seed Veronika Kudermetova on Friday before finding her best game.

She said on Amazon Prime: "Well, why not, if losing the first set will guarantee me victory, why not?"

Kasatkina, the eighth seed this week, won the Phillip Island Trophy in Melbourne last month so is chasing a second WTA title of the year.

She is relishing the clash with Gasparyan, saying: "It's cool to have players of different styles. Tomorrow's a final so you've just got to go out there and try to show your best tennis."

An all-Russian final was already guaranteed, given the host country locked down all four semi-final places, and it will be the 30th such WTA title match.

Tokyo 2020 organisers have announced spectators will not be allowed to travel from overseas to watch the Olympic Games this year.

The measure has been taken as part of an effort to reduce the risks of COVID-19 spreading at the delayed Games.

The Games will run from July 23 to August 8, having been set back by a year due to the global health crisis.

Also affected will be the Paralympics, which runs from August 24 to September 5, with travelling spectators also barred from attending.

The International Olympic Committee (IOC) and International Paralympic Committee (IPC) have been advised of Tokyo's decision and are said by Games chiefs to "respect and accept this conclusion".

In a statement issued on Twitter, Tokyo 2020 said: "Today, on March 20, we reported to the IOC and IPC that we would not accept overseas spectators to Japan in order to realise a safe and secure event.

"We will continue to do our utmost to make this summer's event a safe and secure event so that it will be a light of hope for people all over the world."

In a further statement, Tokyo 2020 organisers said tickets purchased by those planning to travel from abroad would be refunded.

They said the coronavirus situation within and beyond Japan "remains very challenging" and pointed to travel across borders being "severely restricted", meaning entry to Japan could not be guaranteed.

"In order to give clarity to ticket holders living overseas and to enable them to adjust their travel plans at this stage, the parties on the Japanese side have come to the conclusion that they will not be able to enter into Japan at the time of the Olympic and Paralympic Games," said the Tokyo 2020 statement.

"This conclusion will further contribute to ensure safe and secure Games for all participants and the Japanese public."

World number five Stefanos Tsitsipas cruised into the Mexican Open final with a routine victory over Italian teenage sensation Lorenzo Musetti in Acapulco on Friday.

Tsitsipas triumphed 6-1 6-3 in 79 minutes to get past 19-year-old Musetti, who had beaten third seed Diego Schwartzman and former world number three Grigor Dimitrov on his run to the semis.

The Greek top seed will play second seed Alexander Zverev in Saturday's final after the German got past countryman Dominik Koepfer 6-4 7-6 (7-5) in their semi-final, which was literally rocked by an earthquake.

The broadcast cameras shook mid-point but play continued as a 5.7 magnitude earthquake was registered to the north of Marquelia, which is to the east of Acapulco.

Tsitsipas holds a 5-1 record against Zverev, who is ranked seventh in the world and made last year's US Open final.

"Sascha is someone I've played against in the past and it's never easy. We're both really hungry and we're both very competitive," Tsitsipas said.

The Greek made light work of Musetti, winning five straight games in the opening set after starting at 1-1.

Unforced errors cost Musetti, who had his moments, but Tsitsipas was on song with 17 of 23 winners off his forehand.

Musetti will move into the top 100 of the rankings for the first time on Monday after his breakthrough week.

"We'll definitely see a lot from Lorenzo in the future, he has a wonderful one-handed backhand and creates lots of opportunities. He showed his level this week," Tsitsipas said.

Eighth seed Ann Li toppled the top remaining seed Zheng Saisai in the quarter-finals of the Monterrey Open on Friday, throwing the field wide open.

Li triumphed 7-5 6-1 over third seed Zheng, who held the highest rank of all remaining players after Sloane Stephens and Nadia Podoroska's first-round exits.

World number 52 Zheng struggled to win on her first serve, with Li converted five of seven break points.

American Li, who is ranked 72nd in the world, will next face Swiss qualifier Viktorija Golubic, who beat Russia's Anna Kalinskaya 6-2 6-4.

On the other side of the draw, Canadian Leylah Fernandez defeated Slovakia's Viktoria Kuzmova 7-5 6-3 and will face seventh seed Sara Sorribes Tormo in the other semi-final.

Sorribes Tormo, who is now the highest ranked remaining player, defeated Anna Karolina Schmiedlova 6-3 7-5.