Top-seeded Jannik Sinner was treated by a trainer and left the court during the third set, seemingly surged in the fourth and then faltered again in the fifth, eventually losing to Daniil Medvedev 6-7 (7), 6-4, 7-6 (4), 2-6, 6-3 in the Wimbledon quarterfinals on Tuesday.

"It's always tricky, because you want to play more points to make him suffer a little bit more — in a good way — and at the same time, you know that he at one point is going to say, `OK, I can not run anymore so I'm going to go full power,"' said the fifth-seeded Medvedev, who will take on defending champion Carlos Alcaraz in the semifinals for the second consecutive year. "And that's what he did."

Alcaraz, the 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. The 21-year-old Alcaraz is coming off a title at the French Open last month and is seeking his fourth Grand Slam trophy.

Over at Centre Court, it was not immediately clear what was wrong with Sinner, who had his heart rate checked while sitting on the sideline before heading to the locker room. The 22-year-old from Italy returned after about 10 minutes and resumed playing, but lost the first game back at love.

After getting broken by 2021 U.S. Open champion Medvedev to fall behind 2-1 in the third, Sinner requested medical attention and leaned back in his chair. He rested his head in a hand at one point while speaking with the trainer before they headed toward 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.

"He was not feeling that good, and then he started playing better," Medvedev said.

Medvedev began finding the space to deliver more winners, compiling 13 in the closing set alone, and broke for a 3-1 lead, then held for 4-1 and was on his way back to the semifinals and a rematch against Alcaraz.

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 Emma Navarro 6-2, 6-1 in less than an hour.

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

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 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 carried a nine-match winning streak into Tuesday, including a grass-court title at Halle, Germany, last month. He 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 are gone from Wimbledon before the semifinals. That year, Roger Federer lost in the quarterfinals, and Simona Halep in the third round.

Medvedev had lost his five most recent matches against Sinner, including in the final of the Australian Open in January. That day, Medvedev took the first two sets, before Sinner clawed all the way back to win in five for 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.

Ottawa's Gabriela Dabrowski and partner Erin Routliffe of New Zealand advanced to the women's doubles quarterfinals at Wimbledon with a 6-3, 6-1 win over Elena-Gabriela Ruse of Romania and Marta Kostyuk of Ukraine on Tuesday.

Dabrowski and Routliffe, seeded second at the All England Club, scored the only break of the first set to take a 5-4 lead before winning the deciding game on serve.

Ruse and Kostyuk double-faulted while facing break point to give Dabrowski and Routliffe a 3-1 lead in the second set.

The 2023 U.S. Open champions coasted from there, picking up another break to go up 5-1 then holding serve to win the match.

Dabrowski and Routliffe will next face the eighth-seeded team of Czechia's Barbora Krejcikova and Germany's Laura Siegemund.