Roger Federer turns 40: a look back (33 images)

Switzerland's Roger Federer competes at the Nasdaq 100 Tennis Championship in Key Biscayne, Fla., on March 31, 2002. Andre Agassi defeated Federer 6-3, 6-3, 3-6, 6-4 to win the men's final. Photo by Susan Knowles/UPI

U.S. Open champion Federer poses for the media in New York's Times Square after defeating Australia's Lleyton Hewitt on September 12, 2004. Photo by Ezio Petersen/UPI

Reigning U.S. Open champion Federer reacts as he defeats to Andre Agassi during the men's final match at the U.S. Open Tennis championship in New York City on September 11, 2005. Photo by Monika Graff/UPI

Federer poses with his championship trophy after his match with James Blake at the men's finals of the Pacific Life Open in Indian Wells, Calif., on March 19, 2006. Federer won the tournament for the third straight year. Photo by David Silpa/UPI