Defending champion Novak Djokovic will take on third seed Stan Wawrinka in the US Open final after both men won semi-finals in punishing conditions.
Djokovic beat 10th seed Gael Monfils 6-3 6-2 3-6 6-2 in New York, with the Frenchman adopting unusual tactics to try and counter the world number one.
Stifling humidity was still a factor as Wawrinka beat Japan's Kei Nishikori 4-6 7-5 6-4 6-2 in the second semi-final.
"It's really humid, really hot. I knew it would be tough," said Wawrinka.
Djokovic, 29, had treatment on both shoulders during the first semi-final, while Monfils could barely move at times in punishing conditions.