Kei Nishikori stunned world No.4 David Ferrer in his US Open debut, taking a five-set marathon to become the first Japanese man in the modern era to reach the round of 16.
The 18-year-old Nishikori, who is ranked 126th in the world, defeated Ferrer 6-4 6-4 3-6 2-6 7-5 today in a match that lasted three hours, 25 minutes on the Louis Armstrong Stadium court.
"I still can't believe it," said Nishikori, who tried but failed to qualify for the US Open last year. "I was playing great. This is the biggest win for me."
After squandering a two-set lead, Nishikori stepped it up in the fifth set, clinching the victory on his third match point.
Nishikori is just the second Japanese to reach the fourth round of any grand slam in the modern era. Shuzo Matsuoka made it to the 1995 Wimbledon quarter-finals.
By reaching the fourth round, he surpassed countrymen Jun Kamiwazumi (1973) and Toshiro Sakai (1971), who advanced to the third round of the US Open before being eliminated.
The unseeded Nishikori will next face Juan Martin Del Potro of Argentina.
Nishikori became the first Japanese in 16 years to capture an ATP title by winning the Delray Beach tournament earlier this year.
Nishikori, who was ranked 281st at the end of 2007, won 61 per cent of his first serve points and converted 8-of-14 break point chances on Saturday.
He clinched the match by hammering a forehand winner to the open court on his third match point and second match point of the final game.
Spain's Ferrer survived the first match point in the ninth game of the fifth set by hitting a backhand winner. Nishikori was broken two points later when he miss-hit a shot off the top of his racket, allowing Ferrer to close the gap 5-4.
"He is a very good player. He serves very well," Ferrer said. "I fought a lot but Nishikori played better than me."
Ferrer, who appeared in his first grand slam semi-final at the US Open last year, finished with 59 unforced errors but he made Nishikori work for the victory in a tight fifth set. He knocked out Rafael Nadal to reach the semis.
However, the 26-year-old's frustration boiled over in the fifth set when he slammed his racket to the ground after having his serve broken in the fourth game.
Nishikori has trained for the past five years at the Bollettieri Academy in Florida.
