INDIAN WELLS, Calif. -- Australian Open champion Novak Djokovic outlasted Roger Federer 6-3, 3-6, 6-2 to stay undefeated this season and reach the BNP Paribas Open final while knocking the Swiss star from the No. 2 spot in the world on Saturday.
Djokovic and Federer will switch spots when the latest rankings are released on Monday, with the Serbian moving up to No. 2 and Federer slipping to third with an 18-3 mark this season. All three of his losses have been against Djokovic, who is 17-0.
"It's the crown for my achievements this year. I think I deserve it," Djokovic said. "I've played the best tennis of my life in the last three months. I have been very dedicated, very professional, and I want to keep on going."
Neither of them had lost a set in reaching the semifinals, although Federer had a tougher time, dropping 29 games in eight sets, while Djokovic had lost just 12 games in eight sets -- the fewest games lost in four matches in an ATP Masters 1000 tournament since 1990.
Nadal improved to 31-4 all-time at Indian Wells, where he won titles in 2007 and '09.
It was the third time in the tournament's 25 years that the world's top three men reached the semifinals.
Sania Mirza of India and Russian Elena Vesnina defeated eighth-seeded Americans Bethanie Mattek-Sands and Meghann Shaughnessy 6-0, 7-5 to win the women's doubles title in their third tournament together. The winners will split $237,000.
Federer became just the fourth player to take a set off Djokovic this year when he won the second. Federer lost to him in straight sets in the Australian Open semifinals and in the Dubai final earlier this year.
"My approach to the matches against Roger is maybe different than it was in the past two years. Right now I kind of have more self-belief when I step on the court against him," Djokovic said. "Before it was, 'Let's hope that I can play well.'"
Djokovic broke Federer to open the third set, then staved off two break points and hit a forehand winner that kissed the sideline to hold for 2-0.
Federer broke back when Djokovic double-faulted at love-40 to tie the set at 2-all. But Federer double-faulted to lose the next game as the Serb won the final four games to close out the win. Djokovic reeled off 11 straight points in that stretch, breaking Federer once more on a forehand winner in the corner.
"It's really important to get the upper hand in some part of the match against an opponent like Roger," he said. "When you have the chance, you better use it because he can come back easily. I could feel that."
With Djokovic serving on his second match point, Federer sent his forehand return long. Djokovic pounded his heart with his right fist, delighting his Serbian flag-waving female fans who screamed for him.
"I had my chances. I know I wasn't far away at all because I really had him going," Federer said. "I guess he escaped. I guess confidence is a big thing for him at the moment."
Del Potro, formerly No. 4 in the world, has been on a roll the last month, when his ranking surged from 484th to No. 90 with strong showings in the United States. The Argentine reached the semifinals in San Jose and Memphis, and then won the title in Delray Beach, Fla.
At Indian Wells, he beat three seeded players to reach the quarterfinals, then caught a break when injured Tommy Robredo withdrew, leaving him fresher to face Nadal and try to become only the second player to beat the Spaniard four consecutive times in his career.
Nadal needed a third-set tiebreaker to beat Ivo Karlovic in the quarters.
Against Del Potro, Nadal started out slowly on a mostly cloudy day in the desert, with the temperature dipping to 70 degrees -- 20 degrees cooler than earlier in the week. He got broken on his forehand error in the second game and Del Potro held for a 3-0 lead.
Del Potro held again for a 4-1 lead before Nadal won the final five games, including an ace down the middle in the 10th game that gave him the first set.
"After that, I started to put more balls inside, play higher to his backhand, and trying to get the right rhythm," Nadal said. "I did well. I played a few good games. He had a few more mistakes than usual. That helped me a little bit."
Tied 2-2 in the second, Nadal earned the set's lone break after two deuces to go up 3-2. He closed out the match by serving a 40-love game, punctuated by Del Potro's backhand service return error on match point.
"Of course, in the beginning I felt really good, but that means nothing. Against Rafa, you have to play in the beginning until the last point very nice tennis," Del Potro said. "If you don't take your opportunities, you will lose. He broke me twice: one in the first, one in the second set, and that's it. The match is over."