Roger Federer has had nothing short of an amazing career at the U.S. Open. Federer won five straight Opens starting in 2004. Federer constantly displayed his mastery of the hard courts during those five years. He has won many of the U.S. Open series tournaments that lead up to the U.S. Open. In the quarter finals of 2004 when Federer began his amazing run at Flushing Meadows, he faced one of the fiercest competitors that the sport of tennis has ever seen, Andre Agassi. In a five set match, Federer proved once again that he was going to be a legend of the game. The next year, Federer and Agassi met once again on center court, but this time in the finals. In a four set match Federer won his second U.S. Open title. It was in 2009 that Federer was finally dethroned on the courts of the U.S. Open. Juan Martin del Potro, a young Argentine who had finally broken through on the tour, made an amazing run to the finals, defeating Nadal on his way. Federer unusually seemed to lose his cool after a dispute about the rules of the challenge system, which seemed uncharacteristic of him during a slam final. Del Potro managed to win the match with his flat, heavy forehand and surprisingly good movement. Nevertheless, Roger Federer has had an amazing career at the U.S. Open.