Novak Djokovic

Novak Djokovic of Serbia returns a shot against Roger Federer of Switzerland during the men's semifinal of the Sony Ericsson Open at the Crandon Park Tennis Center on April 3, 2009 in Key Biscayne, Florida. (Matthew Stockman, Getty Images / April 3, 2009)

A vulnerable Roger Federer isn't used to playing the role of underdog. But he's getting used to it.

The second-seeded Federer, who seemed to have a clear path to the final once his arch nemesis and world No. 1 Rafael Nadal was dispatched by Argentine Juan Martin Del Potro on Thursday, stumbled again, this time against Serb Novak Djokovic 3-6, 6-2, 6-3 in Friday's early semifinal at the Sony Ericsson Open.

Playing in blustery conditions, the normally stoic Swiss unraveled after littering the purple courts with a bucketful of forehand errors. Trailing 0-2, 15-0 in the third set he was set up for an easy midcourt forehand, but inexplicably he found nothing but net.

He then fired his most accurate stroke of the windy day when he slammed his Wilson racket into the court. At first, Federer, who recently was named the tour's Sportsman of the Year for the fifth straight year, was serenaded with boos from the shocked gallery. But then realizing that perhaps a little emotion would help turn the match around, the jeers turned to cheers.

"It must've been here against Rafa,'' a teary-eyed disconsolate Federer said was the last time he broke a racket in anger, referring to the 2005 Sony final when he trailed Nadal two sets to none before coming back to win. "There's so much wind today and once you start feeling bad it's tough to regroup. One end you had the sun in your eye, it was really tough on the ball toss. .. But it's the same for both players. Once one guy gets the upper hand, the other guy is a bit uncertain.

"It's tough but he struggled big time in the first set so you know to finish worse than him … I had a great effort by finishing even worse than him.''

Federer's serve was broken just once all tournament before the semifinal, but Djokovic broke it six times, reaching his seventh Masters 1000 finals. He is 4-2, including a victory here in 2007.

Nothing helped the seemingly lost 13-time Grand Slam champion, who has had trouble dealing with his newfound status as the second best player in the world. Federer, 27, picked up his crumpled stick, but was unable to pick up his game and soon he was down two breaks and 0-4.

The third-seeded Djokovic has had his own identity crisis with the fans as the entrenched No. 3 player in the world. He has been accused of feigning injuries when trailing in matches, and has been criticized by players for his imitations of them.

He tried to let Federer back in with two double faults sandwiched between a silly drop shot to hand one of the breaks back. At 4-2, Djokovic served out a love game for a 5-2 lead. Federer, playing his most relaxed game since the first set, ended his serve with consecutive aces to force Djokovic to serve for the match.

No problem as again Federer donated with three more forehand errors, giving him 35 on the day to set up match point. After returning a 126-mph serve, a 10-stroke rally ensued with Federer slicing back Djokovic forehand blasts until the last one drifted long, causing the Serb to pound his chest and his countryman to wave the many flags in the stands.

Other than Federer tossing his racket in disgust he shocked the media even more when he thanked 'God,' for the end of the hard court season. This coming from the player who has won 38 tournaments on hard courts, including eight of Slams on the concrete, as well as two here in 2005-06.

"It's the end of the hard court season,'' he said. "I don't care anymore. I'm moving over to clay, a new chapter.''