It was the latest finish in tournament history at nearly half an hour. Alcaraz, 19, dropped to the ground and covered his face in disbelief as he sealed the match point after coming dangerously close to defeat in the previous set.
The 6-3 6-7 6-7 7-5 6-3 win lasted five hours and 15 minutes – Alcaraz’s second straight marathon match after his five-set win over Marin Cilic in the previous round.
Sinner served 5-4 for the match in the fourth set, but Alcaraz struck back, winning the next three games in a row to force a decider – and salvaging a match point in the process.
The 21-year-old Sinner then led with a break in the fifth set as well, only for Alcaraz to once again refuse to flex. He will become the youngest men’s Grand Slam semifinalist since compatriot Rafael Nadal in 2005 and the youngest at the US Open since Pete Sampras in 1990.
“I always say that you have to believe in yourself all the time,” Alcaraz said in his on-pitch interview. “Hope is the last thing you lose … I have to stay in the game and try to stay calm, but it’s difficult to stay calm in this moment.”
Playing in his third Grand Slam quarterfinal, Alcaraz got off to a quick start on Wednesday when he broke Sinner’s serve three times in the opener.
He had chances to extend his lead with set points in the second, but Sinner held on and forced a tiebreak, during which the Italian saved another set point and leveled the match.
In set number three, Alcaraz led with a break, serving 6-5 for the set, but a resilient Sinner broke back and sailed through the resulting tiebreak to serve.
The 21-year-old now had the advantage but this time it was Alcaraz’s turn to dig deep and save a match point in fourth before coming on from a collapse in fifth.
“Throughout the game, five hours and 15 minutes, I feel great physically,” Alcaraz told reporters. “Of course the level of tennis that we played was really, really high. But I felt great.”
The rollercoaster match will likely be remembered as one of the biggest in US Open history, with an engaged crowd watching as it lasted into the wee hours.
The standout moment was arguably a baseline shot behind Alcaraz’s back while he was under pressure in the second set. He followed it up with a backhand pass to win the point, gesturing solemnly into the stands.
“This match is crazy. I drive to the airport at 6am but I refuse to sleep and miss this,” American star Coco Gauff tweeted.
The win means Alcaraz could still become the youngest No. 1 in men’s rankings next week after leaders Daniil Medvedev’s early exit from the tournament.