MANNHEIM (Germany), Dec 14: Ukraine’s Wladimir Klitschko retained his WBO, IBF and IBO world heavyweight titles on Saturday with a technical knockout of Hasim Rahman in round seven.

The referee stopped the fight after Klitschko, 32, landed a series of punches to Rahman’s head and the American retreated to the ropes, barely able to stand. The Ukrainian had already knocked him down in round six.

Klitschko improved his record to 52 wins and three defeats.

Rahman was unable to get past Klitschko’s left jab to land the kind of big punch that saw him beat world champion Lennox Lewis in 2001, when he knocked out the Briton with a right hook to record one of the biggest upsets in boxing history.

Rahman, 36, had never really regained that form. He replaced Alexander Povetkin as Klitschko’s opponent in October after the Russian pulled out of the bout with a foot injury.

Earlier, former heavyweight champion Riddick Bowe made a successful comeback at the same venue after 3-1/2 years out of the ring. Despite looking overweight, 41-year-old Bowe beat German Gene Pukall on points on the undercard.—Reuters