NEW YORK -- As a trainer hacked through the several dozen yards of tape wrapped around Fernando Gonzalez's ankle, Rafael Nadal tried to stay focused in his changeover chair.
He jiggled his legs deliberately (with typical Rafaian intensity) and his independent left eyebrow arched quizzically as he surveyed a largely empty Arthur Ashe Stadium on Saturday afternoon. It was just another delay in a series of setbacks that turned his quarterfinal match into a watery three-day marathon.
When it was over, nearly 42 hours after it began, Nadal leaned back, closed his eyes and blew out his cheeks in a gesture of comic relief. Cricket contests can take that long, but a bloody tennis match?
Nadal needed just a little over a half-hour to finish off Gonzalez, completing a second-set tiebreaker and all six games of the third set, 7-6 (4), 7-6 (2), 6-0 before the rain returned to the National Tennis Center.
"Important thing is be calm, be ready to come back," Nadal said later. "When you come back in a situation like today, anything can happen, no? Because it's a little bit [of a] lottery. Depends on the first two points."
Finally, we're down to four.
Although the women's draw was in tatters by the third round, the elite men delivered early, and often. Sunday's semifinals feature a pair of sparkling matchups: No. 1-seeded Roger Federer versus No. 4 Novak Djokovic and No. 3 Rafael Nadal versus No. 6 Juan Martin del Potro.
This is smoking stuff, especially since the higher seeds, in both cases, have lost two of three matches this year to the lower seeds.
Federer is the five-time defending champion and has won 39 straight matches here. In his consecutive run to 21 previous semifinals, Federer has lost only three times, most recently in straight sets to Novak Djokovic at last year's Australian Open.
"I think he's put himself in this position," Federer said of Djokovic. "He's done well against me in the past, but I beat him in Cincinnati and hope I can build on that."
Federer won 6-1, 7-5, but Djokovic held a set point. This is a far more important match for Djokovic, who hasn't been to a major final since winning in Melbourne 19 months ago. Moreover, this is the 22-year-old Serb's first Grand Slam singles semifinal this year.
"Now that I've done it," Djokovic said after dispatching Fernando Verdasco, "I feel kind of a relief."
Two years ago, on his way to the final here, Djokovic won over the fans at Arthur Ashe with impersonations of Nadal and Maria Sharapova. Last year, Djokovic's critical remarks about Andy Roddick in an on-court interview drew boos from the fans at Arthur Ashe. But a lively postmatch hitting session with John McEnroe delighted the crowd, and he has been hosting the children of Sept. 11 victims for his matches. A win over Federer would probably complete the rehabilitation of his relationship with the people of New York.
"It feels like 2007, when I played the finals here and did all these crazy things, impersonating the players," Djokovic said. "It was really a lot of enjoyment playing with McEnroe the other night. It was unexpected. It just came out. It was good."
So was del Potro in his run to the semifinals. He dropped only six games in his last two sets against Marin Cilic in the quarters and his serve has never looked better. Del Potro is the leader among the remaining players in aces (68) and has converted more break points (32) than anyone in the tournament.
More importantly, the 20-year-old Argentine has a mental edge going into the match: He's beaten Rafa the past two times out, most recently a month ago in Montreal.
With Nadal nursing an abdominal muscle injury, del Potro has a legitimate chance to reach his first major final. The only other time del Potro has progressed this far was back in Paris. He showed incredible poise for one so young, pushing Federer to five sets.
"I was so close to beat him," del Potro said. "I learn many things. I want to be a good player in the future. I'm very happy to be on my way."
The U.S. Open is the only major missing from Rafa's résumé. Last year, after winning at Roland Garros and Wimbledon, he never had a chance here.
"The last year [I] was totally mentally destroyed," Nadal said. "Mentally this year I am perfect, no?"
Mentally, maybe. Physically? Not so much. He missed more than two months when the tendinitis in his knees flared up and is fresher than he's ever been this late in the year. With his win over Gonzalez, Nadal guaranteed that when the new ATP World Tour rankings come out, he will return to his No. 2 spot, back ahead of Andy Murray.
It's been an eventful fortnight for Rafa. There was that three-day match, the abdominal injury and after his fourth-round win over Gael Monfils he was visited by Noam Aorta, a fan(atic) who ran onto the court.
"The guy was really nice," Nadal said. "He said, 'I love you,' and he kiss me. For me, it wasn't a problem."
Greg Garber is a senior writer for ESPN.com.