NEW YORK - Kei Nishikori pumped his fist as a forehand from his opponent flew into the net, clinching his victory in the match. He let out a deep breath, but still didn't seem to understand the essence of what had just happened at the US Open on Wednesday.
Nishikori knocked out No. 3 seed and this year's Australian Open champion Stan Wawrinka 3-6, 7-5, 7-6 (9-7), 6-7 (5-7), 6-4 at Billie Jean King National Tennis Center, making him the first Japanese man to reach the semifinals here since Ichiya Kumagai in 1918.
"I don't know how I finished this match," said Nishikori. "This is really a nice surprise."
Following his second straight match of more than four hours (4:15 to be exact), Nishikori had added a new chapter to the history of Japanese tennis after coming out on top in a five-set struggle.
It was obviously a fierce battle. Nishikori grabbed the third set in a tiebreak, but the fourth set also went to a tiebreak, which the 24-year-old lost.
"My frustration level was extremely high [at that point], but I just tried to put that out of my mind and looked to play good tennis," Nishikori said.
The match seemed to be headed toward mental test for the players, but Nishikori put an end to that notion by wrapping things up. Leading 5-4 in the final set, Nishikori converted a break chance against Wawrinka to seal the victory.
Japan's top male player had undergone minor surgery on his right foot on Aug. 4. He only returned to practice a week before the US Open began, and was still unsure if he would play up until the day of his first-round match. Nevertheless, Nishikori has moved well on the court and advanced to the semifinals with no hint of a foot issue.
Nishikori has sometimes struggled physically, playing well in tournaments before being struck by injuries or ailments midway through.
Winning back-to-back five-setters is proof he has made big strides in his physical and mental development. His victory over world No. 4 Wawrinka came after he knocked off No. 6 Milos Raonic.
"It's a confidence boost to beat two top 10 players," Nishikori said. "The next opponent will be even tougher, but I want to get to the final."
Nishikori, who lived in the United States where he developed as a junior player, even got chants of "Kei" from the spectators.
With momentum on his side, Nishikori will look to keep his run going.