Kei Nishikori stunned Novak Djokovic to become the first Japanese player ever to reach a grand slam singles final.
World number one Djokovic was bidding to reach his fifth consecutive US Open final but Nishikori played superbly to win 6-4 1-6 7-6 (7/4) 6-3 and set up a clash with either Roger Federer or Marin Cilic.
The 24-year-old world number 11, who also becomes the first Asian man to make a slam singles final, said: “I don’t know what’s going on.
“I was a little bit tight, especially with my first semi-final in a grand slam. It’s just an amazing feeling, beating the number one player and playing much better than the last couple of matches.
“I’m so happy. It was tough conditions but I guess I love to play long matches and I hope I can recover well for the final.
“I hope it’s big news in Japan. I feel the support from Japan, even from the TV. It’s 4am in Japan but I hope a lot of people are watching.”
It has been a productive year for Nishikori since he was beaten in the first round by Britain’s Dan Evans at Flushing Meadows 12 months ago.
He broke into the top 10 for the first time in May and, by beating Stan Wawrinka on Wednesday, became the first Japanese man to reach a grand slam singles semi-final in 79 years.
Nishikori’s progress had been held up by his physical fragility, and there were doubts before the tournament whether he would play after undergoing minor foot surgery.
But the 24-year-old certainly answered a few critics by following up a five-set win over Milos Raonic in the fourth round, which finished at 2.26am, by also going the distance to defeat Wawrinka.
And if Nishikori was tired or nervous going into his first semi-final, he did not show it, more than matching Djokovic from the back of the court.
An early break came and went but Nishikori was the one dictating a lot of the points and he placed a forehand return onto the outside of the line to move ahead again at 4-3.
And this time he held onto his advantage to take the set.
Nishikori is one of the fastest players on tour and he generates terrific pace off both his forehand and backhand for a man of only 5ft 10in.
His talent has never been in doubt but he credits former French Open champion Michael Chang, who joined his coaching team in December, with helping him develop his mental strength.
He could not stem the Djokovic tide in the second set, though, the 2011 champion stepping up the aggression and winning five games in a row.
It was a very hot day and Nishikori toiled away to hold serve in the third game of the third set.
The question was at what cost, but he got a second wind and combined backhand pass with forehand winner to break the Djokovic serve in the eighth game.
That left him serving for the set but, having been so cool, Nishikori wobbled, double-faulting on break point.
Djokovic roared as he held to make it 5-5 but the world number one was strangely passive and paid for it in a lacklustre tie-break.
And when he handed over his serve meekly at the start of the third set, the alarm bells really started ringing. He had three chances to break straight back but Nishikori saved them all.
Djokovic certainly appeared to be struggling more with the heat and he never really looked like clawing his way back, as he has done from similar situations on so many occasions before.
Nishikori kept attacking and, with Djokovic serving at 3-5, brought up two match points.
The top seed saved the first but went long on the second, allowing a delighted and slightly stunned Nishikori to celebrate the biggest win of his life.