Former US Open runner-up Alexander Zverev has beaten Jannik Sinner 6-4 3-6 6-2 4-6 6-3 to move into the quarter-finals of the year's final grand slam.
The 26-year-old German's victory in four hours 41 minutes, the longest match at Flushing Meadows so far this tournament, ended in the early hours of Tuesday morning and earned him a meeting with defending champion and top seed Carlos Alcaraz.
"I'm here to play. That's what I love doing. I don't know how it will end up but I'll give it my absolute best like I always do," Zverev, the Tokyo Olympics gold medallist, said on facing the Spaniard.
"I'll fight til the last moment ... I'll be ready. Of course, I have to recover after this physical match but I'll be ready."
Both Zverev, the 12th seed who is rediscovering his best form after an ankle injury wrecked his 2022 season, and world No.6 Sinner struggled with fatigue and cramp during their epic clash.
Sinner, the 22-year-old Italian who made the 2020 final, won the second and fourth sets but was broken in the second game of the fifth and never recovered.
"I would have loved to play a little shorter, that's for sure, but last year when I wasn't able to play, this is what I missed," Zverev said.
"Playing past 1:30am in front of a packed crowd on Arthur Ashe Stadium. There's nothing better.
"This is one of the best moments of my career after my comeback, after everything. I'm looking forward to what's next."
Earlier inside Arthur Ashe Stadium, Alcaraz wasted little time in booking his last-eight spot.
The defending champion and world No.1 was a comprehensive 6-3 6-3 6-4 winner over 22-year-old Italian Matteo Arnaldi in under two hours.
Unseeded Arnaldi, 61st in the world, put out Aussie Jason Kubler in the second round and British No.16 seed Cameron Norrie in the last 16, but Alcaraz was a different matter.
Third seed Daniil Medvedev brought Alex de Minaur's campaign to an end, winning 2-6 6-4 6-1 6-2 to move into the last eight for the fourth time in five years.
Medvedev, the 2021 champion, led their head-to-head meetings 4-2 coming into the match but the 13th-seeded Australian had won their last two contests, including a straight sets quarter-final win at the Canadian Open tune-up event.
"Today, first set felt like he couldn't miss," said Medvedev.
"I felt like he was playing top level. I was like, Wow, he's actually destroying me right now.
"To turn around the match like this is always a great feeling. It gives you a lot of confidence for next matches."
Next up is a clash against fellow Russian Andrey Rublev, who is godfather to Medvedev's daughter.
"We have a great relationship," Medvedev said.
"To have a friend like this is great but on the court we both want to win. We're not going to be friends in two days."
Rublev ended Jack Draper's breakthrough run in New York.
The British No.4, in the second week of a grand slam for the first time, fell 6-3 3-6 6-3 6-4 to the eighth seed.
Draper, 21, has endured an injury-hit year and slipped from a ranking of 38, in January, to outside the top 100.
A shoulder problem saw him miss Wimbledon and also threatened his participation at Flushing Meadows.