Argentine Del Potro dreams of being world No. 1

U.S. Open 2009 winner Del Potro of Argentina attends a news conference in Buenos Aires, Argentina on Sept. 16, 2009. (Xinhua/Martin Zabala)

U.S. Open 2009 winner Del Potro of Argentina gestures in Buenos Aires, Argentina on Sept. 16, 2009. (Xinhua/Alejandro Amdan)

BUENOS AIRES, Sept. 16 (Xinhua) -- Argentine tennis player Juan Martin del Potro, winner of the U.S. Open, said on Wednesday that his "maximum dream is to be number one" of the world.

Del Potro, who arrived on Wednesday here, said his coming goal is to win the Masters Cup of London, to be played by the eight best players of the season from Nov. 22 to 29.

During a press conference, Del Potro said Swiss player Roger Federer "continues marking a difference with the rest".

"My maximum dream is to be number one, but I have a long way. Now there are players over my game level, beyond the results of this tournament," Del Potro said.

Del Potro defeated on Monday Federer 3-6, 7-6 (5), 4-6, 7-6 (4)and 6-2, in a match of 4 hours and 6 minutes.

After winning the last Grand Slam of the year, Del Potro rose to number 5 in the world rankings.