NEW YORK -- Roger Federer pulled a fast one in the fourth round before the rain came, sneaking in his win over Juan Monaco in the early morning hours Tuesday. And then he watched as rivals Rafael Nadal and Andy Murray ran afoul of the wet weather here at the U.S. Open.
Thursday night, Federer seemed to be in the catbird seat again with a quarterfinal night match against Jo-Wilfried Tsonga -- with Nadal and Murray contemplating their quarters scheduled for Friday. At the age of 30, Federer will take all the rest he can get and this looked suspiciously like a serious competitive advantage.
But then, after a glorious day of sunshine -- after all the other major matches had been played -- the karma turned. It rained on the Federer parade with the Swiss champion serving at 3-2. He sat in the locker room for more than an hour, while Djokovic -- who had left hours earlier -- was probably enjoying a nice meal.
Federer came out focused and yet relaxed after the rain delay. After winning the first set, he intently watched super fan Cameron Hughes -- the dancing guy in the "I Love New York" T-shirt -- stir up the crowd. He was still laughing when he walked back onto the court.
With surprising ease -- for Tsonga had beaten him twice in the past two months -- Federer hammered the powerful Frenchman 6-4, 6-3, 6-3.
"Doesn't matter, straight sets or five sets," Federer said afterward, "as long as you keep progressing in the tournament."
At Wimbledon, Tsonga came back from a two-set deficit -- the first time Federer had ever lost from that commanding position. Did that memory haunt him in Thursday night's third set?
"It's true, the Wimbledon match does come back into your mind, especially when he has a break point in the third," Federer said. "Very happy the way I'm playing and moving right now."
Federer will meet Djokovic in what promises to be a scintillating Saturday semifinal.
"This year he's really been able to step up," Federer said. "The biggest challenge in tennis. I'm up to it."
Djokovic beat Federer three times early this season, most notably in the Australian Open semifinals. But Federer stunned him in the semifinals at Roland Garros, ending his 43-match winning streak. This, one will decide their 2011 three-match series at the majors. You have to believe the winner has a pretty good chance of winning the tournament.
The funny thing? The one guy here who really doesn't need any help, got a terrific break Thursday being the first one into the semifinals.
"For the top half, it could be [an advantage]," Djokovic had said earlier, before Federer was stalled. "It has to be advantage in some ways, because we finished our fourth round couple days ago, and then today I finished my quarterfinals and I have a day off until my semis, where the other guys have to play day after day."
He didn't sound terribly sad.
"That's the way it is," Djokovic continued. "You can't fight it. You can't complain. It's the Mother Nature that doesn't allow us."
Djokovic, it should be mentioned, is now an extraordinary 62-2 for the season -- 60 matches over .500. Not even the Philadelphia Phillies can say that.
Most of the way through Day 11 of the U.S. Open there were still only two men who hadn't dropped a set -- Nadal and Djokovic.
And then there was one.
Djokovic and Serbian Davis Cup teammate Janko Tipsarevic hooked up in a physical fourth-round match on Arthur Ashe and, for just a moment, Djokovic blinked. After nearly winning the first set, Tipsarevic took the second in a tiebreaker. He retired due to a leg injury in the fourth set with the score 7-6 (2), 6-7 (3), 6-0, 0-3 -- but he threw a major scare into Djokovic.
In the first game of the fourth set, Djokovic sprinted to net and ran down a drop shot (successfully), sliding to an abrupt stop. Djokovic raised his fist to the crowd, but after taking a few steps, he fell to his knees. The friction between shoe and court was too much for the big toe on his left foot, which was bleeding when the ATP World Tour trainer attended to it during an injury time out.
Following the 3-hour, 27-minute match, Djokovic didn't sound concerned about the toe. Rather, he talked about coming out more aggressively for his Saturday semifinal.
"I think the last two matches I have been starting very slow," Djokovic said. "I'm very passive. All the credit to my opponents, I mean, especially Janko today who has been playing amazing tennis. So credit to him that he pushed me back from the baseline.
"But, yeah, I will try to have that in the next match."
Bet on it.
Greg Garber is a senior writer for ESPN.com.