South Korea's Park Tae-hwan smiles after winning the men's 400m Freestyle event at the FINA Swimming World Championships in Shanghai, China, Sunday, July 24, 2011.
15 Faces to Watch at the 2012 London Olympics
The next Usain or Phelps – global icons based on their dominant performances in Beijing -- could come from field hockey or judo. Here are 15 competitors to keep your eye on in London. -- By Carla Thorpe