Several famous boxing fans flew to Las Vegas on May 1, 2010, for one of the most anticipated welterweight fights in recent memory: Floyd Mayweather Jr. vs. Shane Mosley. Everyone from Will Smith to Mariah Carey to California Gov. Arnold Schwarzenegger watched Mayweather rally back from a round 2 scare to defeat Mosley in a unanimous decision. See the celebrity spectators in the crowd. Will Smith pays his respects to boxing's greatest, whom he played in a 2001 biopic.