Serena Williams turns 40 in September. Roger Federer hits that milestone the month before. No one knows how many more French Open appearances each will make, and this year’s tournament ended for both on Sunday.

Williams fell way behind and could not put together a comeback against a much younger and less-experienced opponent in the fourth round at Roland Garros, losing 6-3, 7-5 to Elena Rybakina — who wasn’t even born when the American made her tournament debut in 1998.

Asked whether that might have been her last match at the clay-court major, Williams responded: “Yeah, I’m definitely not thinking about it at all. I’m definitely thinking just about other things, but not about that.”

Her defeat came hours after Federer withdrew, saying he needed to let his body recover ahead of Wimbledon after a long third-round victory that ended at nearly 1 a.m. on Sunday.

Wimbledon — which Federer has won eight times and Williams seven — begins June 28.

“I’m kind of excited to switch surfaces,” Williams said. “Historically I have done pretty well on grass.”

She has won 23 Grand Slam singles titles; Federer has won 20. They are two of the sport’s greatest and most popular players, so it was quite a blow to the tournament, its TV partners and tennis fans to see both gone from the French Open field one after the other — and a week after Naomi Osaka pulled out, citing a need for a mental health break.

Williams has won the French Open three times. But the American hasn’t been past the fourth round in Paris since she was the runner-up in 2016.

Rybakina is a 21-year-old from Kazakhstan who is ranked 22nd. This was just the seventh Grand Slam appearance for Rybakina — and the first time she ever made it so much as past the second round.

“When I was small, of course, I was watching her matches on TV. So many Grand Slams,” Rybakina said.

Against Williams, whose right thigh carried a heavy tape job, Rybakina hit big, flat serves. She dealt with, but managed to steady, her nerves. She even produced the occasional return winner off Williams’ speedy and spectacularly gifted serve, breaking her five times, including in the next-to-last game.

“I knew that the serve was going to be difficult for me to return. She’s powerful, but I was ready,” Rybakina said. “Then, after few points, I felt … comfortable.”

Rybakina said she followed her coach’s strategy of sending shots to Williams’ backhand side and trying to stay away from her forehand.

Every time Williams appeared as if she might turn things around, she could not quite get the momentum fully in her favor.

Down a quick break in the second set, she got to 2-all. Williams then was down 4-3 in the second set but pulled even again when Rybakina sailed a forehand well wide to get broken.

In the next game, Williams gave away the opening point when, near the baseline, she failed to get out of the way of a shot from Rybakina that was flying long. Williams smiled ruefully and leaned over, resting and propping herself up with her racket.

Repeatedly one sort of mistake or another undid Williams. She ended up with 19 unforced errors and only 15 winners.

“I’m so close. There is literally a point here, a point there, that could change the whole course of the match,” Williams said. “I’m not winning those points. That, like, literally could just change everything.”

Since winning the 2017 Australian Open while pregnant for her most recent major singles title — No. 23 set a record for the professional era — Williams has come close to tying Margaret Court’s all-time mark of 24. That includes four runner-up finishes at Grand Slam tournaments, most recently against Bianca Andreescu at the 2019 U.S. Open.

But since then, Williams has been beaten twice in semifinals, and once each in the third and fourth rounds. Last year at the French Open, she withdrew before the second round, citing an injured left Achilles.

Federer, meanwhile, never had pulled out of a Grand Slam tournament once he had started competing in it until now.

Rybakina next will meet Anastasia Pavlyuchenkova with a semifinal berth on the line; they’re playing doubles together and are scheduled to play a third-round match in that event Monday. Pavlyuchenkova advanced with a 5-7, 6-3, 6-2 victory over two-time Australian Open champion Victoria Azarenka.

The other quarterfinal on that side of the women’s draw is going to be Paula Badosa against Tamara Zidansek. Neither has been this far at a major tournament, either.

One of those four players will become a first-time Grand Slam finalist next weekend.

Stefanos Tsitsipas is still looking for his first major final, too, and he reached the quarterfinals at Roland Garros for the second year in a row by eliminating 12th-seeded Pablo Carreno Busta 6-3, 6-2, 7-5.

Tsitsipas next faces No. 2 Daniil Medvedev, who has won six of their previous seven meetings.

Medvedev is a two-time Grand Slam finalist — at the 2019 U.S. Open and this year’s Australian Open — but was 0-4 for his career in Paris until now. He advanced Sunday by eliminating No. 22 Cristian Garin 6-2, 6-1, 7-5.

The other quarterfinal on that side of the field will be unseeded 22-year-old Alejandro Davidovich Fokina against No. 6 Alexander Zverev or Kei Nishikori. Davidovich Fokina beat Federico Delbonis 6-4, 6-4, 4-6, 6-4.

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