Kei Nishikori defeated American Donald Young in straight sets to advance to the quarterfinals of the U.S. National Indoor Tennis Championships on Thursday.
Fifth-seeded Nishikori, who is playing in his first tournament since reaching the last 16 of the Australian Open in January, won 6-3, 6-3 in just over an hour to book a meeting with Marin Cilic in the last eight on Friday.
"I overpowered my opponent with my ground strokes and was able to get forward and be aggressive. I played perfect tennis," said Nishikori.
Ranked 22nd in the world, Nishikori is making his comeback having taken time out of the ATP Tour after the Australian Open to focus on recovering from a left knee problem.
He wore a black knee support in Thursday's game.
"It was just a precaution," said Nishikori. "My knee didn't give me any problems whatsoever."