Del Potro wins US Open

The 20-year-old Argentine, who remained in the match by winning two tiebreaks, gained confidence as he moved through his first career Grand Slam final.

He ultimately charged to victory, breaking Federer in the last game to end their four-hour, six-minute struggle.

The 6'6" Del Potro lay down on his back and covered his tear-streaked face with his hands after the 28-year-old Swiss sailed a backhand long on the Argentine's third championship point.

"I had two dreams this week," the sixth-seeded Del Potro said at the trophy presentation. "One was to win the US Open and the other one is to be like Roger.

"One is done, but I need to improve a lot to be like you," he said, looking at Federer, winner of a record 15 Major titles.

"You fought until the final point. You are a great champion."

Del Potro delivered on his promise as a rising talent, ending Federer's 40-match US Open winning streak and depriving the world number one from matching American Bill Tilden's feat of notching six US titles in a row in the 1920s.

Federer, who was two points away from taking a two sets to none lead, was not at his precision best.

He successfully landed only half of his first serves, committed 11 double faults and made an uncharacteristic 62 unforced errors, including many wild mis-hits.

"I got off to a good start and had many more chances to make a difference," Federer, who capitalised on just five of 22 break points, said.

"He hung in there and gave himself chances, and in the end he was a better man."

Del Potro became the second Argentine to win the US men's crown, joining compatriot Guillermo Vilas, who won on clay in 1977, and attended the final in Arthur Ashe Stadium.

The Argentine had never beaten Federer in six previous meetings, losing to the Swiss master in the semi-finals of the French Open after taking a two-sets-to-one lead.

Del Potro struggled in the first set.

"In the beginning of my match I was so nervous. I couldn't sleep last night," he said. "Roger started very good. I was down, missing badly with my serve and that's an important weapon in my game.

"Then I started believing in my game and it changed."

Federer, who took the only service break of the opening set in the second game with a dazzling forehand winner, launched after a hard sprint to his backhand side, was serving for the second set at 5-4, 30-0 when Del Potro overtook him.

Del Potro cashed in a break point reached on a forehand winner ruled good after a challenge by the Argentine, the first of several calls that visibly rankled Federer.

The set went to a tiebreak, which Del Potro won 7-5, but the see-saw contest swung back to Federer's favour in the third set after Federer lashed out at the chair umpire over a call.

Upset that Del Potro was allowed to challenge a call on game point in the ninth game as Federer was about to sit for the changeover leading 5-4, the Swiss cursed while complaining to the umpire that the challenge was not made on time.

Del Potro went down quietly in the next game, double-faulting on the last two points and holding his hands over his face in despair.

Desperate to stay in the match, Del Potro showed his fighting spirit in the fourth set, pouring on the pressure after exchanging service breaks.

He held serve at love to force the tiebreak and won the first three points of the decider to take charge.

The lanky Argentine made the lead stand up, clinching the tiebreaker 7-4 off two forehand errors from Federer.

Questions about fitness and stamina had dogged Del Potro in the past, but in the fifth set he dominated.

Del Potro broke the French Open and Wimbledon champion in the second game and cemented his advantage by breaking the Swiss master again in the final game.

The final tally showed Del Potro with 37 winners off his huge forehand.

Federer, whose last defeat at Flushing Meadows came against Argentine David Nalbandian in the fourth round of the 2003 tournament, tried to look on the bright side of a season that included his first triumph on the clay of Roland Garros.

"You can't have them all," he said. "I've had an amazing summer and a great run."