LONDON — Jannik Sinner felt ill. He was dizzy, and he hadn't slept well the night before. Wimbledon's top-seeded man, who recently attained the No 1 ranking, definitely did not want to quit playing against Daniil Medvedev in the quarterfinals, but things were not looking good.

Sinner was treated by a trainer and left the court during the third set Tuesday, then briefly surged before faltering again down the stretch, eventually losing to a more-aggressive-than-usual Medvedev 6-7 (7), 6-4, 7-6 (4), 2-6, 6-3.

"I was struggling physically," said Sinner, who had won his past five matches against Medvedev, including a five-setter in the final of the Australian Open in January. "It was not an easy moment. I tried to fight with that what I had today."

It wasn't enough.

Not against the crafty Medvedev, the 2021 US Open champion, who will now face Carlos Alcaraz in the semifinals at the All England Club for the second consecutive year.

"It was a bit of an up-and-down match, in a way, from both sides," Medvedev said.

Alcaraz, the defending champion and No 3 seed, took a bit of time to get going in his quarterfinal, but once he did, there was no stopping him during a 5-7, 6-4, 6-2, 6-2 victory over 12th seed Tommy Paul of the United States on No 1 Court.

"We try just to find solutions," said Alcaraz, coming off a title at the French Open last month and seeking his fourth Grand Slam trophy. "For me, obviously, it's going to be really difficult to play my best tennis every match."

Against Paul, Alcaraz raised his level after a so-so opening set, putting together a 26-12 advantage in winners over the last three.

"When he starts building energy and building momentum, it feels a little bit different than most of the other guys," Paul said. "He can play some seriously amazing tennis."

Alcaraz, who leads Medvedev 4-2 in head-to-heads, said it would be tough to face the former US Open winner, picking out his ability to get the ball back in play.

"The most difficult thing about facing Daniil, or the most special thing about him, is he can reach every ball," he said.

"Well, he is like a wall. Every ball bounces back. I feel like I can hit an unbelievable shot, and the ball is going to bounce back."

Medvedev, for his part, said three-time Grand Slam champion Alcaraz, 21, was a danger anywhere on the court.

Alcaraz said he was delighted that opponents feared him in such a way, because it meant they had to "focus on every shot".

"You know, whatever shot you hit, he can hit a winner from there," said Medvedev, "so you try to make his life difficult. You try to hit the shot as good as you can.

"Maybe he goes for it and he cannot make it, but that's pretty special because there are not many players like this. Carlos can do whatever from any position, and that's not easy to play against."

Over on Centre Court, it was not immediately clear what was wrong with Sinner, who leaned back in his sideline chair, rested his head in a hand and had his heart rate checked, before heading to the locker room. During a later changeover, Sinner draped a towel over his head.

While he did regain his usual verve, particularly on his booming forehand, and pushed the match to a fifth set — the 36th this fortnight and the most at any Grand Slam tournament in the Open era, which dates to 1968 — Sinner could not get over the line.

Even though he won more points (164-160), accumulated more winners (61-56), made fewer unforced errors (49-45), hit more aces (17-15) and finished with far fewer double-faults (11-4).

"It's a tough one to swallow," Sinner said.

Medvedev began playing closer to the baseline than he often does. The 28-year-old Russian found the space to deliver more winners, compiling 13 in the closing set alone, broke for a 3-1 lead in the fifth, and was on his way back to the semifinals.

"Today," Medvedev said, "a lot of tactical things worked well."

Against Sinner in Australia, Medvedev took the first two sets, but Sinner clawed all the way back to win his first Grand Slam title.

That result dropped Medvedev's career record in major finals to 1-5.Now he's one victory from a seventh such appearance.

"Hopefully, I can win some more Grand Slams," Medvedev said. "I believe in myself. I believe in my tennis."

In the women's quarterfinals, Donna Vekic reached the final four at a major for the first time in her 43rd Slam, defeating qualifier Lulu Sun 5-7, 6-4, 6-1, and French Open runner-up Jasmine Paolini eliminated No 19 seed Emma Navarro 6-2, 6-1 in less than an hour.

"If you had told me before Roland Garros that I would get to the final there and the Wimbledon semifinals," Paolini said with a laugh. "I would have said you were crazy."

Until last week, she was 0-3 at the All England Club, and until Tuesday, was 0-3 against Navarro.

Navarro got past four-time major champion Naomi Osaka and reigning US Open champ Coco Gauff earlier in the tournament.

"I know this isn't the last time I'm going to be in the quarterfinals of a Grand Slam," Navarro said. "I know I'll be back."

Vekic, a 28-year-old from Croatia, pondered quitting the sport on multiple occasions — including as recently as right before play began at Roland Garros in May.

"I didn't have any energy, any motivation to keep practicing, keep pushing, because I felt like the last couple of months I've given everything for tennis, and I wasn't getting the results that I kind of expected," Vekic said.

"Now I'm the semifinals," Vekic said. "Not just in tennis, (but) in life, things can turn pretty fast."

Sinner was a Wimbledon semifinalist a year ago and moved up to No 1 in the ATP rankings, replacing Novak Djokovic there, on June 10 after getting to the semifinals at the French Open.

His exit follows that of the No 1 women's seed, Iga Swiatek, in the third round.

It is the first time since 2018 that both the top woman and top man have exited Wimbledon before the semifinals. That year, Roger Federer lost in the quarterfinals, and Simona Halep in the third round.

Agencies