Rafael Nadal continued his pursuit of an elusive first US Open title after dispatching Feliciano Lopez in straight sets to reach the quarter-finals.
The eight-time Grand Slam champion swept his fellow Spaniard away 6-3 6-4 6-4 inside two hours in a match that ran into the early hours of the New York morning following some drawn out fourth-round matches earlier in the day.
After racing through the first set, a single break in the subsequent two were enough for the world number one to progress to the last eight where he will face another compatriot in Fernando Verdasco.
"I think I am playing well, but I am not playing yet at my highest level," said Nadal, who is bidding to become only the seventh man in history to win a career Grand Slam of all four major tournaments.
"I am playing better and better every day and I had to play a little bit better this match.
"To be in quarter-finals of the US Open without losing a set and without losing a serve, two things must work really well - the concentration and the serve."
Elsewhere, Verdasco staged a thrilling fightback to overcome David Ferrer 5-7 6-7 (8-10) 6-3 6-3 7-6 (7-4).
He recovered from two sets down and then also a break down in the decider before then fighting back from 4-1 down in the final set tie-break.
Meanwhile, Andy Murray's conqueror, Stanislas Wawrinka, came out on top of a marathon four-and-a-half hour 7-6 (11-9) 6-7 (5-7) 7-5 4-6 6-4 tussle with Sam Querrey.
Former semi-finalist Mikhail Youzhny will face the Swiss in the quarter-finals following his 7-5 6-2 4-6 6-4 win over Tommy Robredo.