INDIAN WELLS, Calif. (AP) — Roger Federer lost again, this time in one of the biggest tennis upsets in memory.

Mardy Fish, an American ranked 98th, shocked No. 1 Federer in straight sets Saturday, with the lopsided score — 6-3, 6-2 — making it even more of a stunner.

Fish, who pulled off by far the biggest of the upsets he's strung together this week in the Pacific Life Open, moved into Sunday's final against No. 3 Novak Djokovic, who ousted defending champion Rafael Nadal.

Federer, the Swiss star who has seemed almost invincible most of the past five years, has looked vulnerable so far this season.

He hasn't reached a final and has lost three times, including defeats by eventual champion Djokovic in the Australian Open semifinals, and by Andy Murray this month in the first round at Dubai.

The 26-year-old Federer, who was slowed by mononucleosis early in the season, doesn't seem overly concerned.

He breezed through his first three matches at Indian Wells without losing a set, then had a walkover in the quarterfinals when Tommy Haas withdrew because of a sinus infection.

"Today it's hard to judge, because Mardy took everything on the rise; not many rallies out there," said Federer, a three-time champion in the desert tournament. "But all in all, I'm happy with the way the week (went) for me." In Sunday's women's final, Ana Ivanovic will face Svetlana Kuznetsova.