Stan Wawrinka won against Japan's Kei Nishikori 4-6, 7-5, 6-4, 6-2 on Friday to set up a US Open title clash with world number one Novak Djokovic.
World number one Djokovic beat France's Gael Monfils 6-3, 6-2, 3-6, 6-2 late on Friday.
On Sunday, he will defend his title in the US Open final where he will be seeking a third major of the season and 13th of his career.
Two-time Grand Slam winner Wawrinka asserted himself in the later stages, withstanding onslaught from sixth-seeded Nishikori despite the toll taken on by both players due to extreme humidity.
Three seeded Wawrinka said, "It was tough conditions, it was really hot and humid so I knew it would be tough."
"It's crazy to be in the final."
Wawrinka saved a match point in a fourth-set tiebreaker of a third-round victory over Briton Dan Evans, before making his way to the title match.
In addition to that epic five-setter he's played three four-setters.
He spent 14 hours 47 minutes on court, reaching the semis, a figure that swelled with his three-hour, seven-minute win over Nishikori.
Nishikori, after his five-set quarter-final triumph over world number two Andy Murray, took a 3-2 lead against Wawrinka and closing it out with an ace on set point.
He broke Wawrinka again to open the second, but he was beginning to find his range and broke back to level the set at 2-2.
Wawrinka was able to save five break points to hold trailing 0-40 in the seventh game and knotted the match at two sets apiece with a break in the 12th game.
He took the third and took Nishkori at love for a 2-0 lead in the fourth, he appeared to be on his way.
In the fifth game he found himself down 0-40 and after the Swiss saved two break points Nishikori had it back on serve when Wawrinka fired a backhand wide.
Wawrinka said,"He dictated play early tonight, put pressure on me and gave me no time."
"I had to wait and fight and make him uncomfortable. He got tired and I started to be more aggressive."
Wawrinka said he was looking forward to his first US Open title tilt.
"I am really excited, I want to enjoy the moment," he said. "I have seen the final here on TV many times, watching Roger, Rafa, Novak."
Although Djokovic holds a 19-4 record over Wawrinka, he is excited to play against him.
"To play Novak again it will be very special," he said.
(WION with inputs from agencies)