Defending champion Rafael Nadal dug deep to win the longest match of this year's US Open in a classic five-set quarter-final against Dominic Thiem - which finished at 2:03am local time.
World number one Nadal lost the opening set 6-0 after being outpowered by the Austrian ninth seed in New York.
However, the 32-year-old Spanish top seed recovered to lead two sets to one before Thiem levelled in a tie-break.
Nadal edged a tense fifth-set tie-break to win 0-6 6-4 7-5 6-7 (4-7) 7-6 (7-5).
The 17-time Grand Slam champion clinched victory when Thiem hit an overhead smash long on the first match point, the drama continuing until the last shot in an epic encounter lasting four hours and 49 minutes.
Nadal jumped over the net to console his Austrian opponent at the end, the pair embracing as those left inside Arthur Ashe Stadium rose to their feet to give them a thunderous ovation.
"I said to Dominic: 'I'm very sorry and keep going.' He has plenty of time to win. He will have his chances in the future without a doubt," Nadal said.
Asked about how he got through the tense moments, Nadal added: "Suffering is the right word. It was a great battle."
He will play Argentine third seed Juan Martin del Potro, the 2009 champion, in Friday's semi-finals.
"It is good to have two days that probably give me the chance to be 100% in the semi-finals," Nadal added.