Heavyweight champion Wladimir Klitschko of Ukraine, left, knocked down contender Tony Thompson, of the United States, right, during their world heavyweight championship title bout at the Stade de Suisse soccer stadium in Bern, Switzerland, Saturday, July 7, 2012. Wladimir Klitschko stopped Tony Thompson in the sixth round to retain his WBA, IBF and WBO heavyweight title belts on Saturday. (AP Photo/Keystone/Alessandro della Valle)