Kei Nishikori became the first Japanese man in 81 years to reach the semifinals in the US Open, by wearing out No. 3 seed Stan Wawrinka in five sets.

Becoming the epitome of endurance under pressure in this year's tournament, the 10th seeded Nishikori was the last man standing for the second time in two days. Afterwards it seemed hard for him to even raise an arm in celebration after the 4 hour, 15 minute marathon match.

"I don't know how I finished the game, but I'm happy," an exhausted Nishikori, who had a medical timeout in the third set to have his right foot taped, told the Arthur Ashe Stadium crowd after clinching victory. "I feel amazing. I'm very happy to come my first time semis. I hope I can recover again and hopefully I can play 100 per cent tennis next round."

He fell in the first set 3-6, before coming back to beat Wawrinka 7-5, 7-6 (7), 6-7 (5), 6-4, on Wednesday.

He had extra reason to be tired afterward, because just the day before, he took over four hours to beat Canadian Milos Raonic, a match that ended after 2:30 in the morning.

Nishikori showed up ready to play Wednesday, though, and he proved it on the court.

Nishikori's coach, and US tennis legend Michael Chang, laughed when he was asked by the Gospel Herald about his sleep the night between the two matches.

"I think we got a few hours," he said. "I think we were in bed by 4 something."

Chang said he was proud of Nishikori for being able to fight through, especially after getting down early.

Wawrinka, who won his first Grand Slam title at the Australian Open in January, was impressed by Nishikori's endurance, too.

"Even at the beginning he looks like he's going to die on the court, but he's there," Wawrinka said. "Physically, he's there. Even at the end of the match, even. We were both quite tired in the fifth set. I try not to show."

Chang, who has been working with Nishikori since December, said things had been going well.

"This was a unique opportunity," Chang told the Gospel Herald. "There haven't been a whole lot of Asians, not Asian men, doing well on the ATP tour."

Chang, a devout Christian, said it was good to know God was in control when he faced tough battles on and off the court.

"You go out there and do the best you know how, and you leave the results to God," he said. "It takes a lot of pressure off."

Nishikori, 24, has two days to let the pressure grow or decline before the semifinals on Saturday, when he will play the No. 1 seed, Novak Djokovic. You can bet that if his coach has a say in how the time off goes, they will have patience, and know they can trust God if they do their best.

Nishikori became the first Japanese man to make a semifinal of the United States championships since Ichiya Kumagae in 1918.

Go here to watch Chang's interview with the Gospel Herald.

Follow Don Pittman on Twitter @DonaldPittman.