Federer won 6-3, 6-4 in the semifinals of the BNP Paribas Open on Saturday night in a match that got started nearly three hours late because of rain. Wind whipped the court and temperatures plunged 20 degrees from Friday's high in the 80s.
"I had a no-lose mentality," said Federer, who has been sick with a cold during the tournament. "I didn't expect myself to play so well, and this is sometimes when you can pull off the biggest wins of your career. That's where I'm happy I gave myself a chance this week."
No. 3 Federer will play 11th-ranked John Isner in Sunday's final, a rematch of their Davis Cup showdown last month in which Isner won on clay in Switzerland.
"Without taking anything away from John in Switzerland, the conditions were extremely tough for both of the players. It was altitude, it was a clay that was virtually unplayable. Every second bounce had a bad bounce in it," Federer said. "So tomorrow hopefully will be a bit more normal."
Isner fired 20 aces, including one at 135-mph on his fourth match point, to beat top-ranked Novak Djokovic 7-6 (7), 3-6, 7-6 (5) in the other semifinal.
Nadal's grumpy expression matched his out-of-sorts body language as what he called the "crazy wind" picked up. The cold made Nadal's favored topspin shots more difficult and made the ball bounce lower than it would in the heat.
"He was better than me, and that's it," Nadal said. "I understand what I had to do too late to have more chances to win the match."
Nadal netted a forehand to give Federer match point when rain drops slickened the lines on the court and the chair umpire halted the action. The players sat in their chairs trying to stay warm.
"I was just really hoping that we don't have to go off court because that would have really been tough on the fans, too," Federer said.
Minutes later, Federer got up and smacked an ace wide to Nadal's forehand side, giving him his first win over Nadal since last year's ATP World Tour finals. The Swiss star still trails their series 18-10.
"It's not like I haven't beaten him in 10 years," Federer said, laughing.
Information from The Associated Press was used in this report.