Daniil Medvedev of Russia reacts after winning a point against Jannik Sinner of Italy during their quarterfinal match at the Wimbledon tennis championships in London, Tuesday, July 9, 2024. (AP Photo/Alberto Pezzali)

LONDON (AP) — Jannik Sinner felt ill. He was dizzy. 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 Daniil 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 U.S. Open champion who now will face Carlos Alcaraz in the semifinals at the All England Club for the second consecutive year.

“Was a bit 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 No. 12 Tommy Paul at 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.”

Over at 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, a 28-year-old from Russia, began playing closer to the baseline than he often does. He 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.