Heavyweight champion Wladimir Klitschko of Ukraine, left, fights contender Tony...

Heavyweight champion Credit: APWladimir Klitschko of Ukraine, left, fights 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. (July 7, 2012)

BERN, Switzerland -- Wladimir Klitschko stopped Tony Thompson in the sixth round to retain his WBA, IBF and WBO heavyweight title belts Saturday night.

The 36-year-old champion Klitschko, 58-3 with 51 knockouts, floored Thompson with a big right hand near the end of the fifth round at Stade de Suisse, and the 40-year-old American never recovered.

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BERN, Switzerland -- Wladimir Klitschko stopped Tony Thompson in the sixth round to retain his WBA, IBF and WBO heavyweight title belts Saturday night.

The 36-year-old champion Klitschko, 58-3 with 51 knockouts, floored Thompson with a big right hand near the end of the fifth round at Stade de Suisse, and the 40-year-old American never recovered.

The Ukrainian champion dropped Thompson again in the sixth, and referee Sam Williams gave the challenger a standing count before stopping the fight.

In 2008, Klitschko stopped Thompson in the 11th round.

Thompson, who was the mandatory challenger nominated by the IBF, dropped to 36-3.