Juan Martin Del Potro of Argentina kisses the trophy during the awarding ceremony for the men's singles final against Roger Federer of Switzerland at the U.S. Open tennis tournament in New York, Sept. 14, 2009. Del Potro won 3-2. [Xinhua/Shen Hong]

Argentine Juan Del Potro upset world number one Roger Federer 3-6, 7-6(5), 4-6, 7-6(5), 6-2 to win the U.S. Open, the first Grand Slam title of his career on Monday.

At the age of 20, the sixth seed broke the Swiss mogul earlier in the final set to push Federer to the corner. The Swiss saved two match points in the final game before Del Potro notched up the stunning win.

Del Potro is the first Argentine since Guillermo Vilas to win the New York title. The Argentine's win also means that Federer's bid to become the first man in modern history to win six straight trophies at the same event was dashed.

Juan Martin Del Potro (R) of Argentina and Roger Federer of Switzerland pose during the awarding ceremony for the men's singles final at the U.S. Open tennis tournament in New York, Sept. 14, 2009. [Xinhua/Shen Hong]