INDIAN WELLS, Calif. — No. 98 Mardy Fish stunned No. 1 Roger Federer 6-3, 6-2 today in the Pacific Life Open semifinals.

Fish, pulling off by far the biggest of a string of upsets he's put together in the tournament, dominated the match against the three-time Indian Wells champion.

The defeat, even more surprising because it was so lopsided, continued Federer's frustration this season. The once invincible-seeming Swiss star has lost three times this year, the first two to Novak Djokovic in the Australian Open semifinals and Andy Murray in the opening round at Dubai.

The 26-year-old Federer had been slowed by mononucleosis earlier in the year, but said during the Indian Wells tournament that he was OK again. He hadn't lost a set in the tournament until his match against Fish.

Federer looked like just another player Saturday, with his backhand especially mediocre. He hit just one winner and had 13 unforced errors with his backhand.

Fish, meanwhile, kept constant pressure on him, serving seven aces to Federer's two, and peppering the lines with hard groundstrokes. Fish hit 26 winners to Federer's 14.

Fish, who had never beaten as many as two top 10 players in one tournament, made it three in a week at Indian Wells. He defeated No. 4 Nikolay Davydenko and No. 7 David Nalbandian, as well as No. 24 Lleyton Hewitt, before beating Federer.

The 26-year-old Fish, who ended Federer's 41-match win streak against Americans dating to a 2003 loss to Andy Roddick, moved into Sunday's final against Djokovic, a 6-3, 6-2 winner over defending champion Rafael Nadal.

Australian Open champion Djokovic is ranked No. 3 to Nadal's No. 2.

Avenging last year's loss to Nadal in the Indian Wells final, the 20-year-old Serb served eight aces to two by Nadal, and hit 20 winners to the Spaniard's 11.

The match included several long, spectacular rallies when each dashed around the court making difficult returns. More often than not, Djokovic would end those rallies by driving a winner down the lines, or Nadal would finally miss a shot.

Nadal won last year's championship showdown in the desert 6-2, 7-5. The 21-year-old still holds a 6-3 edge in career matches against Djokovic, but is 2-3 against him on hard courts.

In Sunday's women's final, Ana Ivanovic will face Svetlana Kuznetsova.