Nishikori could find himself up against Marin Cilic for place in semi-finals
Former US Open finalist Kei Nishikori reaches quarter-finals
Kei Nishikori, vying to improve on his US Open runner-up finish in 2014, cruised into the quarter-finals at Flushing Meadows on Monday with a 6-3, 6-2, 7-5 victory over German Philipp Kohlschreiber.
Japan's Nishikori could find himself up against Marin Cilic for a place in the semi-finals in a rematch of the 2014 championship match won by the Croatian.
Seventh-seeded Cilic, who survived a five-set marathon against Australian teenager Alex de Minaur that went into the early hours of Sunday morning, faced 10th-seeded Belgian David Goffin later on Monday.
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Nishikori reached a career-high fourth in the world in 2015, but tumbled down the rankings as he was sidelined for six months by a wrist injury that kept him out of last year's US Open and eventually required surgery.
But he has made brisk progress to the quarter-finals, dropping just one set and benefitting from Gael Monfils's injury retirement in the second round.
After rolling through the first two sets against Kohlschreiber he hit a speed bump as he served for the match at 5-4 in the third.
"That was the toughest moment in the match, serving for the match at 5-4 had a 30-0 lead and he came back really strong," Nishikori said.
"It was a hard situation but I did refocus again after the service break and really played great in the last two games."