MONACO — Alexander Zverev prevailed against Jannik Sinner 5-7, 6-3, 7-6 (5) in a Monte Carlo Masters classic to reach the semifinals of the clay-court season opener on Friday.

Sinner overcame an early break to win the first set, and Zverev repaid the favor in the second. Zverev fought back twice from a break down in the third set and had to force the quarterfinal to a tiebreaker.

In a match with 10 service breaks, half of the tiebreaker points went against serve, and Zverev finally won after more than three hours when Sinner netted.

Second-seeded Zverev will meet defending champion Stefanos Tsitsipas in the semifinals on Saturday.

Tsitsipas overcame Diego Schwartzman 6-2, 6-7 (3), 6-4. The fifth-ranked Greek breezed through the first set, but squandered a 5-2 lead in the second. He had to claw back from 4-0 down in the decider to serve out the match in just under three hours.

“I think I let go,” Tsitsipas said of the missed opportunity to win in straight sets.

“There was a moment in the match where I felt like what I was trying to do out on the court wasn’t really working. I wanted to stay as long as possible on court. I loosened up a little bit and focused on shot after shot … that worked out very well.”

Novak Djokovic’s conqueror, Alejandro Davidovich Fokina of Spain, knocked out Taylor Fritz of the U.S. 2-6, 6-4, 6-3. Davidovich Fokina broke the 10th seed at 3-3 in the decider to line up his first semifinal in a masters event with Grigor Dimitrov of Bulgaria.

“I am enjoying every point,” Davidovich Fokina said. “I stayed focused and believed in myself.”

Dimitrov edged Hubert Hurkacz of Poland 6-4, 3-6, 7-6 (2). The unseeded Bulgarian dropped two match points in the deciding set before taking it in a tiebreaker.

“I didn’t really want to focus much on if I’m going to win or lose, because it’s not always the best thing,” Dimitrov said. “I was seeing quite a few cracks in the way he was attacking the ball, especially in the tiebreak.”