Kei Nishikori became the first Japanese man to reach a grand slam semi-final in the Open Era after a marathon 3-6 7-5 7-6 (9-7) 6-7 (5-7) 6-4 victory over Stanislas Wawrinka.
At 2.26am on Tuesday morning Nishikori completed a five-set victory over Milos Raonic in the fourth round and was forced to go the distance again on Wednesday.
The 10th seed and Wawrinka battled for 4 hours 15 minutes on Arthur Ashe Stadium before Nishikori eventually prevailed in a contest which ran into the time allocated for the night session.
"I started a little bit tight but my body was okay, I was feeling more and more confident, especially getting the third set. I don't know how I finished the match but I'm very happy,” Nishikori said.
"I feel amazing. This is my favourite grand slam. I have good memories here and I'm very happy to be first time in the semis. I hope I can recover again and play 100 per cent tennis next round."
Given Nishikori's exertions, it was no real surprise when Wawrinka raced into a 3-0 lead early on, and that was enough for the Swiss to take the opening set.
But errors started to creep into the 29-year-old’s game as the match wore on, none more so than the double fault which handed Nishikori the second set.
Far from tiring, the Japanese player seemed to be improving as the match went on, his forehand in particular keeping Wawrinka on the run.
The pair traded breaks of serve in the third set and Nishikori even had a set point at 5-2, but eventually a tie-break was needed to decide it.
A vicious forehand gave Wawrinka a set point but Nishikori responded in kind with a stunning backhand winner and wrapped up the set when Wawrinka produced his 55th unforced error.
The toll on Nishikori showed after three games of the fourth set when he took a medical time-out to have his blisters treated but he continued to play high-level tennis to keep pace comfortably with Wawrinka.
Nishikori fought back from 4-0 down in the tie-break to level at 4-4 but missed two forehands wide and Wawrinka landed a huge second serve on the back of the line to level proceedings.
With the match well into its fourth hour they headed into a decider, and it was Wawrinka who finally cracked, serving a double fault to give up two match points at 4-5.
He saved the first but netted a forehand on the second to send Nishikori, who is coached by former French Open champion Michael Chang, into the last four.