NEW YORK -- It isn't often that No. 1-ranked Novak Djokovic is relegated to the secondary stage, but Tuesday night was an extraordinary one at the US Open.
"Look, he's one of the rare players that serves and volleys off the first serve," Djokovic said of Lopez afterward. "It was anybody's game in the fourth set. He had a couple of break points. I played pretty good, very consistent. Very glad to get through in four.
"Obviously, it was frustrating at times, but this was quarterfinals of a Grand Slam. This is what you expect."
The 2-hour, 39-minute match ended at 1:06 a.m. Wednesday before an understandably thinned-out crowd at Arthur Ashe Stadium.
Cilic will be the sixth straight opponent for Djokovic here that has yet to beat him; Cilic is 0-13 against him in his career, including the recent quarterfinals at Wimbledon.
Djokovic, 28, was playing in his 26th consecutive Grand Slam quarterfinal and is now 9-0 in US Open quarters. He has won 40 hardcourt titles, but only one at the US Open, in 2011.
In five previous matches, Lopez, a smooth volleying, forward-moving Spaniard, had taken only one set from Djokovic. But he played a wonderful match Tuesday. In fact, it wasn't until the final tiebreaker that Djokovic finally solved him.
Djokovic won seven of the final nine points.
The good news for Djokovic is he will have two days off before meeting Cilic.
"Semifinals of a Grand Slam is a great achievement," Djokovic said. "Hopefully, I can keep on going."