LONDON -- Defending champion Elena Rybakina booked her place in the Wimbledon third round, but only after surviving a torrid second set against experienced Frenchwoman Alize Cornet, who needed a medical timeout after slipping late in Thursday's contest.
Also Thursday, Russian qualifier Mirra Andreeva went through to the third round after 10-seed Barbora Krejcikova of the Czech Republic was forced to withdraw because of injury after dropping the first set 6-3 and trailing 4-0 in the second.
American fourth seed Jessica Pegula overcame a second-set wobble to dispatch Cristina Bucsa, ranked 74 places below her, 6-1, 6-4 on her way to the third round.
Wild card and 2019 semifinalist Elina Svitolina of Ukraine toppled 28-seed Elise Mertens 6-1, 1-6, 6-1 to move into the third round.
Svitolina will next face former Australian Open champion Sofia Kenin, who came through qualifiers to enter the main draw. Kenin beat Xinyu Wang of China 6-4, 6-3 to back up her victory over seventh-seeded Coco Gauff that ended a streak of three straight first-round exits at Grand Slam tournaments.
On paper, Rybakina's 6-2, 7-6 (2) win looked comfortable enough, but it was far from straightforward as her power game malfunctioned badly after she had looked on course for a quick finish.
The Moscow-born player who represents Kazakhstan slammed winners all over Centre Court in a one-sided opening set and appeared to be racing toward victory against her 33-year-old opponent.
But Rybakina's game went from red-hot to decidedly lukewarm as the wily Cornet, playing in her 66th successive Grand Slam tournament, used her experience to dig in.
As the errors flowed off Rybakina's racket, Cornet was locked in a tense game at 5-5 in which she had five break points before slipping awkwardly on the baseline and needing lengthy treatment, though she eventually carried on.
Rybakina then held serve on her 10th game point but was still looking edgy as she was dragged into a tiebreak.
Eventually the No. 3 seed got the job done, but it was far from convincing in the end.
"I started the match good. I had good energy but in the second set it became tougher," Rybakina said on court. "It was a tricky long game and also Alize's fall. It was a tough match but I'm happy to win in two sets."
She will next face wild card Katie Boulter, Britain's last remaining player in the women's draw, who defeated Viktoriya Tomova 6-0, 3-6, 6-3.
Elsewhere Thursday, Croatia's Donna Vekic came from behind to beat former US Open champion Sloane Stephens 4-6, 1-5, 6-4 and Switzerland's Belinda Bencic also fought back from a set down to send Danielle Collins packing with a 3-6, 6-4, 7-6 (2) victory.
No. 5 seed Caroline Garcia of France dropped the first set before roaring back to overcome 2021 US Open finalist Leylah Fernandez of Canada 3-6, 6-4, 7-6 (10-6).
Estonian former world No. 2 Anett Kontaveit, who is retiring at the end of the tournament at the age of 27, brought down the curtain on her singles career in a 6-1 6-2 defeat to Marie Bouzkova.
"Just a lot of emotions. There's sadness, there's happiness, there's a bit of everything," Kontaveit told reporters.
Czech Karolina Muchova, the French Open finalist seeded 16th at Wimbledon, was hampered by a thigh injury as she lost 6-4, 5-7, 6-1 to Germany's Jule Niemeier in the first round.
Reuters and The Associated Press contributed to this report.