Stan Wawrinka outslugged Japanese sixth seed Kei Nishikori 4-6 7-5 6-4 6-2 in energy-sapping humidity at Flushing Meadows to set up a US Open final against world No.1 Novak Djokovic.
The third-seeded Swiss took a while to get on track as 2014 US Open runner-up Nishikori played a near flawless opening set of the semi-final with just two errors.
The Japanese broke Wawrinka to start the second set, but the Swiss started rolling after breaking back in the fourth game and Nishikori, who went five tough sets to upset second seed Andy Murray in a four-hour quarter-final, began to wither.
Wawrinka, the 2014 Australian Open winner and 2015 French Open champion, broke Nishikori in the last game of the second, third and fourth sets to reach his first US Open final.
"I just tried to little by little play a little bit better, a little bit faster, a little bit heavier," Wawrinka said. "I tried to make him run."
"It's important to not spend energy by being negative and show the opponent that you're struggling."
In the US Open final Wawrinka, who has won the two grand slam finals he has contested will play Djokovic, who he beat to claim his French Open title. Djokovic earlier saw of Frenchman Gael Monfils in a bizarre four-set encounter of his own.
Djokovic took the match 6-3 6-2 3-6 6-2 as the crowd fell in and out of love with the erratic play of Monfils.
In what was one of the more bizarre encounters to unfold on a grand slam court, Monfils was showered with boos one set and cheers the next before exiting Arthur Stadium to a mixture of both.
"He's very entertaining to watch," said Djokovic.
"It was a strange match, as it always is when you play Gael, who is a very unpredictable player. He loves to come up with a variety in his game."
What some viewed as 'tanking', Monfils described as tactics, a well-thought-out 'Plan B' employed when it became clear a more traditional 'Plan A' approach to the match was not going to get him past the Serb.
Djokovic had come out on top in all 12 of their previous meetings.
"Definitely I try to get in his head, try to create something new for him," explained Monfils.
"And that was it. When the guy is too good, playing clean and you're playing not that good, you need to change.
"You just don't want to see it. We can change a little bit. It's not only one way to play tennis. I know it is not natural because first question is you're not competing. I'm competing.
"The change takes guts. It was a great strategy, I think."
Monfils' tactics, while bold, ultimately proved unsuccessful as Djokovic's skill and familiarity with the Frenchman's playing style won out.
