INDIAN WELLS, Calif. -- 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 his 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 by the same score.
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. Obviously, the walkover is sort of an awkward situation, but you have to take them when they come around.
"So semifinals to start off with at the first Masters Series is a good thing, and I hope I can go from here and win in Miami, and on to clay."
Federer said the unexpected day off when Haas pulled out Friday may have thrown him a bit off his rhythm, but said Fish simply played "incredibly."
"When he wanted to attack, everything worked," Federer said. "He would never miss, really, when I needed a miss once in a while."
He said it's impossible to not lose such matches occasionally, adding: "I'm surprised myself that it hasn't happened more in the last five years. You always think one guy can outright dominate you on any given day.
"People weren't able to do it against me, so that speaks for itself. But today, Mardy was really impossible to beat, it almost looked like."
Fish, also 26, ended Federer's 41-match win streak against Americans dating to a 2003 loss to Andy Roddick, and beat him for the first time in their six meetings.
"This obviously wasn't Roger's best day, but hopefully I had a little something to do with that. I put the pressure, extremely, on him from the word go," said Fish, who jumped out to a 3-0 lead in the first set and remained in control the rest of the way.
Asked if he could recall another upset in tennis to equal it, Fish smiled and said, "I don't think I'm that bad."
In a career interrupted by various injuries, he reached his highest ranking, No. 17, four years ago.
Federer looked like just another player Saturday, with his backhand especially mediocre. He managed just one winner and had 13 unforced errors with his backhand. Fish kept constant pressure on him, serving seven aces to Federer's two, and peppering the lines with hard groundstrokes.
He hit 26 winners to Federer's 14 in defeating him for the first time in six career meetings.
Fish, who had never beaten as many as two top 10 players in one tournament, defeated three at Indian Wells. He downed No. 4 Nikolay Davydenko and No. 7 David Nalbandian, as well as No. 24 Lleyton Hewitt, before beating Federer.
Australian Open champion Djokovic, ranked No. 3 to Nadal's No. 2, avenged last year's loss to the Spaniard 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.
"I had more mistakes than usual," Nadal said. "I feel a little bit tired from the last two matches. If you play against a player like Novak, you have to play 100 percent if you want to win.
"He's a very complete player -- very good serve, very good backhand, very good forehand. He moves fast and well. He has very good position on the court."
Djokovic said he's trying to take his fast start to the season in stride.
"I need to stay calm and just go step by step and try to get to my lifetime goal, which is to be No. 1," he said. "It's getting closer, but still, I don't want to go too fast and skip some things. I really need to be consistent with my results in the most important events, major events.
"I started the year in the best possible way, but it's not over yet."