INDIAN WELLS, California (Reuters) - Roger Federer coolly outplayed surprise finalist John Isner 7-6 6-3 on Sunday to become the first player to win the Indian Wells ATP tournament four times.

The Swiss world number three blunted the powerful serving of Isner with a controlled display, edging the American 9-7 in the first set tiebreak then breaking him twice in the second set to triumph in one hour and 21 minutes.

Federer clinched the title when the towering Isner, who upset world number one Serb Novak Djokovic in the semi-finals, dumped a forehand into the net.

The Swiss, who had won three consecutive titles at Indian Wells from 2004-06, raised both arms skywards in celebration as the capacity crowd at the Indian Wells Tennis Garden erupted in applause.

"It's been a tough tournament for all of the players with a lot of sickness," Federer said in a courtside interview, referring to the viral infection that forced eight withdrawals in the first week.

"I'm happy I survived the early rounds to give myself a chance. I couldn't be happier," added the 30-year-old Swiss who crushed his long-time rival Rafa Nadal 6-3 6-4 in the semis at Indian Wells.

On a cool afternoon in the California desert, the opening set went with serve until the 12th game when Federer, leading 6-5, had a chance to break Isner when the American hit a forehand long to advantage down.

However the 6ft-9in (2.05m) Isner saved that with a 129 mph (207 km/h) serve to force a Federer error and the set went into a nail-biting tiebreak where the Swiss squandered further set points when leading 6-5 and 7-6.

The Swiss finally clinched the set on his fourth opportunity when an Isner backhand service return flew long, winning the tiebreak 9-7.

Federer then broke Isner in the seventh game of the second, unleashing a trademark backhand pass down the line to go 15-40 up before winning the next point when the American netted a backhand volley as he charged forward.

After holding serve to lead 5-3, the 16-times grand slam champion broke Isner for a second time to end the match, improving his record for the year to 22-2.

Since his semi-final loss to Djokovic at last year's U.S. Open, Federer has been arguably the hottest player on the men's circuit, winning 39 of his 41 matches.

(Editing by Julian Linden)