PARIS -- Fourth-seeded Kiki Bertens, who had a chance to seize the No. 1 spot in the WTA rankings with a deep run at the French Open, retired during the first set of her second-round match on Wednesday.
Bertens, a 2016 semifinalist and considered a contender for her first major title, was trailing 3-1 against Viktoria Kuzmova on Court Philippe Chatrier when she told doctors that she had no energy and could not continue.
Tears filled Bertens' eyes as she described waking up at 3 a.m., feeling ill.
"Vomiting. Diarrhea. All night long, all day long. I felt a little bit better before the match. I had some sleep, and I just wanted to give it a try," Bertens said. "But then as soon as I start warming up right before the match, it started again. There was not any energy left."
On a sunny morning in the French capital, 19th-seeded Muguruza beat Johanna Larsson 6-4, 6-1 on Court Suzanne Lenglen.
Muguruza won the title at Roland Garros in 2016 when she upset Serena Williams in the final. The Spanish player is expected to face tougher opposition in her next match against ninth-seeded Elina Svitolina, who progressed to the third round without hitting a shot.
Svitolina was set to play 67th-ranked Kateryna Kozlova but organizers said the Ukrainian player withdrew with "intercostal pain." She twice reached the quarterfinals in Paris.
In a match that featured 11 breaks of serve, Stephens could not hold on to a 3-0 lead in the second set and Sorribes Tormo twice had the opportunity to level at one set apiece on her serve. A turning point came in the 11th game when the 22-year-old Spaniard hit two consecutive double-faults to drop serve.
The seventh-seeded Stephens hit a series of winners in the tiebreaker and sealed the match with a backhand down the line.
"Just decided to keep it exciting, to play a bit longer on that court," Stephens joked. "I missed it from last year."
Bertens wasn't the only player to withdraw from the event. Bianca Andreescu, the No. 22 seed from Canada, pulled out of the Grand Slam event prior to her second-round match against Sofia Kenin due to a right shoulder injury.
Andreescu, who won the Indian Wells title in March, also missed the previous two months with the same injury.
Kenin, a 35th-ranked American, will face either Serena Williams or Japanese qualifier Karumi Nara in the third round.
The Associated Press contributed to this report.