Wladimir Klitschko stopped Jean-Marc Mormeck of France in the fourth round of a one-sided fight to retain his WBA and IBF heavyweight titles on Saturday.
The Ukrainian put Mormeck down with a left-right combination, followed by a short left. Mormeck beat the count but looked wobbly and referee Luis Pabon called it over.
''His strategy was to make me tired but I dominated,'' Klitschko said.
Klitschko was credited with the 50th KO of his career but Mormeck said he could have fought on.
''I was frustrated, I could have continued,'' he said in the ring.
Klitschko had already floored Mormeck in the second and completely dominated the affair against the much smaller challenger, who never connected with a clean punch, although Klitschko said he had been hit with one jab.
''My eye is still stinging,'' he said.
Klitschko's record improved to 57-3, while Mormeck dropped to 36-5. Klitschko also held on to the minor IBO and WBO belts.
Mormeck kept trying to come in, lunging forward with his head low and gloves high, often clinging to Klitschko.
A former cruiserweight, Mormeck gave up 6 1/2 inches in height and seven inches in reach to the champion.
Klitschko sent Mormeck down with a big right midway into the second round and it was soon clear he was looking to end the fight early.
Both fighters went sprawling down in the third as they pushed and shoved.
Klitschko picked up the pace in the fourth and connected with his left jab before flooring the Frenchman again.
''I've been around for 15 years and now I have the 50th (KO),'' Klitschko told the crowd at Duesseldorf's football stadium. ''It's a big day for me.''
The fight had been originally scheduled for December but had to be postponed when Klitschko needed surgery to remove kidney stones.
French movie stars Jean-Paul Belmondo and Jean Reno were on hand to watch their countryman.
Older brother Vitali won a unanimous decision against British challenger Dereck Chisora in Munich two weeks ago to retain his WBC belt and said he was hoping his next fight would be against David Haye, the British boxer who lost to Wladimir in July and is officially retired.
Before the fight, Haye challenged Vitali again over a video link.
''I hope the next fight will be against Haye,'' Vitali said in the ring.
