(CNN) -- Sixth seed Juan Martin Del Potro, in his first Grand Slam final, stunned defending champion and top seed Roger Federer to take the men's singles title at the U.S. Open in New York.
Juan Martin Del Potro celebrates after beating Roger Federer during the final on Monday.
The 20-year-old Argentinean took the Swiss world No. 1 to five sets, including two tiebreakers that went Del Potro's way, winning 3-6 7-6 (7-5) 4-6 7-6 (7-4) 6-2.
Del Potro's win, which took four hours and six minutes, ended Federer's five-year reign at the U.S. Open.
Federer, 28, was seeking his sixth consecutive U.S. Open win, which would have equaled the feat achieved in 1925 by American Bill Tilden, who then went on to claim his seventh U.S. Open title in 1929.
Federer had already won this year's French Open and Wimbledon titles and was Australian Open runner-up.
Federer claimed the opening set after leading 3-0 at the beginning, and he achieved an early break in the opening game of the second set as well.
However, Del Potro broke back when Federer was serving for the second set at 5-4 up, with the set eventually going to a tie-break.
Federer had never lost a tiebreak in a U.S. Open final, winning his four previous ones, but Del Potro ended that sequence by taking the tie-break 7-5 to tie the scores.
The third set included a failed challenge by Del Potro, an angry response by Federer to the chair umpire, and a couple double-faults by the Argentine to give the Swiss the set.
Del Potro returned to form in the fourth set that saw Federer near victory but not attain it as his young opponent again won the tiebreak.
Del Potro sped to a 5-2 lead in the fifth set on his serve, and the next game went to deuce before Federer double-faulted and then overshot a backhand to concede the title.
Del Potro won more points than Federer, who had 11 double-faults as well as 13 aces.
Del Potro, a quarterfinalist last year, had reached the finals after beating 16th seed Marin Cilic of Croatia in the quarterfinals and then crushing third seed Rafael Nadal of Spain in the semifinals.
After defeating Nadal, Del Potro had then called the victory "the best moment of my life."