American Amanda Anisimova advanced to the fourth round of the French Open on Friday, after her Czech opponent Karolina Muchova was forced to retire with an ankle injury sustained while leading by a set.
The 25-year-old Muchova, who reached the Australian Open semi-finals in 2021, has been plagued by injuries over the last 12 months.
Having ousted Greek fourth seed Maria Sakkari in her previous match, Muchova took a medical timeout to get her left thigh taped after overturning a 5-1 deficit in the tiebreaker to win the first set.
But there was more pain in store for her when she rolled her right ankle and fell while trying to hit a return at 2-2 in the second.
A tearful Muchova hid her face in her towel on an overcast Court Suzanne Lenglen as the physiotherapist heavily taped the ankle and, though she tried to play on, she failed to win another game.
Anisimova was leading 6-7(7), 6-2, 3-0 when Muchova finally advanced to the net to confirm that she could no longer continue.
"I got some painkillers, I was hoping maybe it's gonna kick in and just tried to play fast balls (thinking) that it will maybe work out but it wasn't working," Muchova told a news conference before breaking off in tears.
Anisimova said ending the match that way was tough. "I feel very sorry for Karolina...," she said. "I just hope that she gets the rest she needs and feels better."
Three years ago the 20-year-old 27th seed became the youngest American to reach the Roland Garros semi-finals since Jennifer Capriati in 1990 and made headlines this year by defeating four-time major winner Naomi Osaka in her first round.
She will face US Open finalist Leylah Fernandez for a place in the quarter-finals, after the Canadian eliminated Swiss Olympic champion Belinda Bencic.
US Open runner-up Fernandez makes fourth round in Paris for first time
US Open finalist Leylah Fernandez edged Olympic champion Belinda Bencic 7-5 3-6 7-5 after a see-saw battle to reach the French Open fourth round for the first time.
The only other time the Canadian left-hander made the second week of a major was on her run to the final at Flushing Meadows last year where she lost to fellow teenager Emma Raducanu.
The 19-year-old Fernandez, who won the girls' title three years ago at the claycourt Grand Slam, saved two set points before winning the marathon first set in 62 minutes and had to rally from an early break down in the decider against the Swiss.
"It was an incredible fight," the 17th seed, who faces American Amanda Anisimova for a last-eight spot, told reporters.
"I think today I was just trusting my game when it mattered the most, and I'm just glad that I was able to trust it enough for me to keep going and keep executing the game plan."
The 14th-seeded Bencic, who won the women's singles gold in Tokyo, hit more winners and committed fewer unforced errors than her opponent in the opening match on Court Philippe Chatrier.
But Fernandez raised her level when it mattered most and, after breaking serve in the 11th game of the decider, held her serve to love to seal the contest in two hours 49 minutes.
The Canadian managed to win a WTA 250 title in Monterrey, Mexico, at the beginning of March but her ride since making the US Open final has been rocked and marked by numerous defeats.
"I have lost a lot of matches to get here," she said. "So I think every match, what's good about my team and I, we were able to use it as a learning experience to see where I can improve and what I'm doing good too.
"It's just the ability to keep learning from every match that we have that helps put me in a position where I can say that I'll just need to trust my game and just fight for every point."