Roger Federer waited at the US Open for hours, eager to get on court for his fourth-round match. Once he finally started playing, shortly before midnight, he didn't take long to win.

Still, Federer enjoyed each of the 82 minutes he needed to hit 14 aces - including four in one game - and generally overwhelm 36th-ranked Juan Monaco of Argentina 6-1, 6-2, 6-0 in a match that ended shortly before 1:15 am local time on Tuesday.

"Other sports start at 8 in the morning, like golf. It's crazy how our schedules change all the time. As tennis players, it makes it extremely difficult to be on your 'A' game every single day," said Federer, whose record 16 Grand Slam titles include five at the US Open.

He watched some of the match before his in Arthur Ashe Stadium - No 1 Caroline Wozniacki's victory over No 15 Svetlana Kuznetsova, which lasted 3 hours, 2 minutes - and also warmed up several times, grabbed a bite to eat, and tried to relax.

"Your body is also jumping out of your skin because you want to go, then you're held back again," he said. "It's tough."

There was also the matter of the mist that started falling early in the third set, raising the possibility of a rain delay - or even a suspension of the match, with a resumption on Tuesday afternoon.

"There was not much margin there for us because it was already so late," Federer said. "So one rain delay and probably they would have sent everybody home."

The third-seeded Swiss had 42 winners and only 21 unforced errors against Monaco in a match that took 1 hour, 22 minutes, less than half the time it took Wozniacki to get through.

As late as Federer-Monaco ended, it doesn't even rank among the 10 latest-finishing matches in tournament history. The record is 2:26 a.m., for a Sept 4, 1993, match in which Mats Wilander beat Mikael Pernfors.

Given all the time-wasting before he got on court, Federer liked the way he played.

"I'm extremely pleased with my reaction out there," he said. "I played really well, crisp, nice. I felt fantastic."

Federer played brilliantly right from the start, taking the first five games - and 20 of the first 25 points - in only 12 minutes. He didn't miss a beat in the second set, hitting four aces in his opening service game.

"Roger was playing unbelievable. I didn't have time to play," Monaco said. "The ball was coming very fast, he was serving unbelievable and I couldn't be quick like I can be in most of my matches."

But he also blamed himself for not preparing properly.

"Maybe I made a mistake: I warmed up about five hours before the match. We'd been waiting for four hours in the locker room," Monaco said. "I got on the court, I'm feeling a little tight. Then during the match, it takes me some time to feel my legs."

Federer reached his 30th consecutive major quarterfinal.

He also earned a rematch against 11th-seeded Jo-Wilfried Tsonga, who pulled off a stunner in the Wimbledon quarterfinals two months ago by becoming the first man to beat Federer in a Grand Slam match after dropping the first two sets.

"It's sure something I'm looking forward to. Look, I live for the big matches, live for playing a guy who is explosive, has got some firepower," Federer said. "I like to play those kind of players, especially now that we're in the deeper stages of the tournament."