Spanish second seed Rafael Nadal responded to the challenge thrown down by 2014 champion Marin Cilic as he battled to reach the US Open quarter-finals with a four-set win.
Nadal, 33, ultimately had too much quality for the Croatian 22nd seed in a 6-3 3-6 6-1 6-2 victory in New York.
Cilic, 30, briefly rediscovered his best form to level before wilting.
Nadal, the 18-time Grand Slam champion, will play Argentine 20th seed Diego Schwartzman in the last eight.
"For some moments in the second set I felt there were too many points in his hands, he was pushing me back, more aggression than me and he hit every ball very strong," said Nadal.