New York - Japan's Kei Nishikori admitted that he felt "tired" during his US Open semi-final defeat to Stan Wawrinka in New York on Friday.
The sixth seed, who beat Andy Murray in an epic four-hour, five-set clash in the quarter-finals, was beaten 4-6, 7-5, 6-4, 6-2 on a hot, humid day at Flushing Meadows.
"I was definitely a little bit tired, especially in the end," the 26-year-old told reporters. "It's not easy after playing Andy five sets.
"He was playing much better the last couple sets. I stopped moving a little bit. He was playing powerful tennis."
Wawrinka will now face defending champion Novak Djokovic in Sunday's final but Nishikori, who lost in the US Open final to Marin Cilic in 2014, was proud of his efforts.
"There was only two more matches to go, so I felt really close and playing at a good level I think these two weeks," he said.
"It's not easy when you have to play number two, number three and (number one) Novak was waiting in the finals.
"It wasn't easy job, but if I could win a little easier the last few matches I could have little more chance today and maybe in the final."
As for Wawrinka, he was thrilled to beat a difficult opponent: "Kei is a tough player and he played well from the beginning.
"I had to wait and fight and make him a bit uncomfortable and he started to get tired.
"That is when I put my game to be aggressive. To be in the final is something crazy."