United States' Michael Phelps celebrates after winning his 8th gold medal after the men's 4x100-meter medley relay final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing. (AP)
This combination of photos shows United States' Michael Phelps holding each of his eight gold medals after the 400m individual medley, 4 x 100m freestyle relay, 200m freestyle, 200m butterfly, 4 x 200m freestyle relay, 200m individual medley, 100m butterfly and the 4x100-meter medley relay at the Beijing 2008 Olympics in Beijing. (AP)
Michael Phelps of the United States goes to hug his mother Debbie, left, and other unidentified relatives after the medal ceremony for men's 4x100-meter medley relay final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing. (AP)
Michael Phelps of the United States is greeted by his mother Debbie and sisters Whitney Flickinger, to the left of Debbie, and Hilary Phelps, after the medal ceremony for men's 4x100-meter medley relay final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics. (AP)
Michael Phelps of the US, right, reaches out to touch the wall ahead of Australia's Andrew Lauterstein during his butterfly leg of the men's medley relay at the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing. (AP)
United States' Michael Phelps, center, celebrates after winning his 8th gold medal after the men's 4x100-meter medley relay final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing, Sunday, Aug. 17, 2008. Others are United States' Aaron Peirsol, left, Brendan Hansen and Jason Lezak. (AP)
United States' Michael Phelps celebrates winning his 8th gold medal after the men's 4x100-meter medley relay final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing. (AP)
United States' Michael Phelps celebrates winning the gold medal after the men's 100-meter butterfly final during the swimming competitions in the National Aquatics Center at the Beijing 2008 Olympics in Beijing. (AP)