World number one Roger Federer battled past Andre Agassi in five sets to set up a US Open semi against Tim Henman.
The Swiss resumed leading by two sets to one after rain stopped play on Wednesday, but Agassi levelled with the only break in a tight fourth set.
The pressure was now on Federer and, in windy conditions, he claimed the decisive break in game eight for a 6-3 2-6 7-5 3-6 6-3 victory.
Federer will meet Henman on Saturday for a place in the final.
The top seed missed two chances to take control of the match as he let break points slip by in the fourth set and Agassi eventually made him pay as he levelled the match.
But it was the Australian Open and Wimbledon champion who looked the more composed in the final set as the wind became increasingly difficult.
"I was a little worried," Federer admitted afterwards.
"I missed chances in the fourth when I had a couple of break points and from then on it was 50-50, who's going to make the mistakes, and he did at the right time for me."
Federer had not played since Saturday following the withdrawal of fourth-round opponent Andrei Pavel and subsequent rain delays, but the Swiss was unconcerned.
"That's what you have to do at the Open, you have to handle the planes, the night matches, the rain, the humidity, the opponents.
"But to beat Andre on Centre Court is a nice feeling."
Agassi admitted he had struggled more than his opponent with the blustery wind.
"Hitting the ball in the centre of the court was a great shot today," said Agassi.
"I just didn't come up with it when I needed it. It was as extreme as it gets. If chairs are blowing over that is a problem."
And Federer is relishing the prospect of facing Henman in what will be a first US Open semi-final for both players, despite his record of just two wins in eight matches against the Briton.
"I'm very pleased," he said.
"I've won two slams already this year and I'm playing Henman next, who I have a bad record against, but luckily I beat him last time in Indian Wells.
"He'll try to charge the net more against me because he knows if he plays from the back of the court he'll have difficulty."