Ash Barty dramatically abandoned her Internazionali d'Italia quarter-final against Coco Gauff on Friday due to a right arm injury.

The world number one was leading 6-4 2-1 in Rome when, with her left thigh also heavily strapped, she pulled out of the match following talks with a trainer.

Barty's decision was precautionary as she will begin her French Open campaign in a little over two weeks' time, bidding to regain the title she won two years ago.

The scare came just hours after world number three Simona Halep announced she tore a calf muscle this week, putting the Romanian's Roland Garros prospects in some doubt.

Providing an update after the match with Gauff, which was interrupted by a rain delay, Australian Barty said: "The pain was becoming too severe so it was important to listen to my body and do the right thing knowing we have a slam."

Gauff, who had hit 12 winners to 15 unforced errors prior to her opponent's withdrawal, will now compete in her first career WTA 1000 semi-final.

Karolina Pliskova remained on course for a second Rome triumph in three years, after saving three match points to edge out Jelena Ostapenko.

The 2019 champion, who also finished runner-up last year, was 5-4 down in the final set when digging deep to hold off her 49th-ranked opponent.

The thrilling match went to a tie-break and Pliskova reeled off seven straight points after losing the opener to advance 4-6 7-5 7-6 (7-1).

"I'm just proud of how I fought," Pliskova said at her post-match news conference. "I'm happy that I stayed in there and fought until the end.

"We played last month, so I knew what was going to be happening. You can never get ready for some of the balls which she's playing."

Petra Martic stands between Pliskova and a place in the final for the third year running after the Croatian defeated Jessica Pegula 7-5 6-4.

Pegula eliminated Naomi Osaka earlier in the week but was second best against Martic, who progressed in one hour and 40 minutes.

Martic trailed 2-0 in the opening set before twice breaking Pegula to move 3-2 in front, but her opponent hit back to make it 5-5 in a tight contest.

However, Martic managed to break in the 11th game and served out the set, before showing her steeliness in the second to remain on course for a maiden WTA 1000 crown.  

Petra Kvitova recovered from a poor start to beat Magda Linette in the first round of the Internazionali BNL d'Italia on Monday.

Linette took just 31 minutes to win the first set in Rome, but world number 10 Kvitova responded superbly to win 1-6 6-0 6-2.

Two-time grand slam champion Kvitova racked up 16 unforced errors in the first set, yet rallied like the great competitor she has proved to be for so long to ensure she will face Vera Zvonareva - conqueror of Christina McHale - in the second round.

The 11th seed from the Czech Republic said: "The first set I started very badly. I was missing almost everything. On the court... [the ball] was bouncing everywhere as well. A little bit windy. I just had to get used to probably everything.

"The beginning of the second set when finally I held my serve and broke her serve, I think since then it was much, much better."

French Open champion Iga Swiatek advanced when Alison Riske retired at 5-4 down in the first set due to a recurrence of a left foot injury.

Swiatek, who will take on Sloane Stephens or Madison Keys in the second round, made 18 unforced errors but had won four games in a row from 4-1 down when the American was unable to continue. 

Coco Gauff battled past Yulia Putintseva 7-5 4-6 6-4 to set up a meeting with 17th seed Maria Sakkari  - who fended off qualifier Polona Hercog 7-6 (8-6) 3-6 6-2.

Amanda Anisimova will do battle with Elina Svitolina, a winner of this tournament twice, after defeating Wang Qiang 7-5 6-3. Jessie Pegula, Jennifer Brady and Petra Martic were among the other winners on day one.

Petra Kvitova brushed aside Jennifer Brady as the defending champion cleared her first hurdle at the Stuttgart Open.

The Czech left-hander was the last winner of the German tournament, beating Anett Kontaveit in the 2019 final, with last year's event cancelled due to the pandemic.

Kvitova was handed a tough opening assignment against Australian Open runner-up Brady, but the American's streak of defeats since that Melbourne final defeat extended to three as Brady lost 6-4 6-3 in an hour and 32 minutes.

Two-time former Wimbledon champion Kvitova, seeded seventh, picked apart the Brady serve once in each set and fended off three break points across the contest to secure her last-16 place.

She was joined in the second round by powerful Belarusian Aryna Sabalenka, as the fifth seed scorched to a 6-2 6-2 win over China's Zhang Shuai.

Earlier, Ekaterina Alexandrova, Kontaveit, Anna Lena Friedsam and Laura Siegemund also went through to the last 16 of the WTA 500 event.

Meanwhile, Fiona Ferro caused a shock at the Istanbul Cup as she landed a 7-5 6-2 first-round win over former champion Petra Martic.

Martic, seeded second this year and ranked 21st in the world, landed the title in Istanbul in 2019 but was rolled over by French player Ferro in an hour and 45 minutes, in a match featuring seven breaks of serve.

Veronika Kudermetova followed her recent maiden title in Charleston with a nerve-jangling first-round win against Bernarda Pera, the fifth seed scrambling through 6-4 3-6 7-6 (7-4).

There was no such toil for top seed Elise Mertens, a 6-2 6-0 winner against Lara Arruabarrena, or for Daria Kasatkina, who dished out a 6-1 6-0 drubbing to Tereza Mrdeza.

Kasatkina is seeking her third title of 2021, having won previously in Melbourne and St Petersburg.

Anastasia Pavlyuchenkova bowed out of the WTA 250 event though, beaten 7-6 (7-2) 6-7 (8-10) 6-4 by compatriot Anastasia Potapova.

Serena Williams and Simona Halep started the season with straight-sets victories in Melbourne a week before the Australian Open gets under way.

Williams and Halep played in an exhibition event with a crowd of 4,000 watching on in Adelaide last Friday and they were back in competitive action three days later.

Legendary American Williams beat Daria Gavrilova 6-1 6-4 to move into the third round of the Yarra Valley Classic.

The fifth seed struck 27 winners to 15 unforced errors on Margaret Court Arena as she set up a meeting with Tsvetana Pironkova, who ousted Donna Vekic 1-6 6-4 6-2.

Williams said: "It was a good match for me. It wasn't easy at all. It was lots of rallies and lots of movement, and she's from here, so she obviously always plays hard. So it was really good and it felt good to clinch that in the end."

Third seed Karolina Pliskova, Petra Martic, Danielle Collins and Marketa Vondrousova also advanced to the last 16 on Monday.

Elsewhere, top seed Halep is through to the third round of the Gippsland Trophy following a 6-4 6-4 win over Anastasia Potapova.

Halep hit 23 winners and broke twice in each set in what was her first official match since October.

Elina Svitolina, the third seed, beat Andrea Petkovic 6-1 6-4, while Coco Gauff, Ekaterina Alexandrova and Jelena Ostapenko were among the other winners seven days prior to the start of the first grand slam of 2021.