Vladimir Klitschko was crowned WBO world heavyweight champion when he defeated title-holder Chris Byrd on points in Cologne.

The three judges voted unanimously in favour of the Ukranian fighter - 120-106, 118-108, 119-107.

The 24-year-old Klitschko, 1996 Olympic champion in Atlanta, avenged the defeat of his elder brother Vitali, who lost the title to 30-year-old Byrd last April in Berlin.

Clearly the stronger, and not only in height and bulk, he tired his American opponent with a series of heavy left and right hooks.

From the sixth round Byrd's eyes were heavily marked and he hit the canvas during the ninth round and 11th rounds.

European champion Klitschko, who lives in Hamburg, took his record to 34 wins, 31 by KO, and just one defeat.

Byrd, Olympic silver-medallist in Barcelona, can take some consolation from the largest purse of his career, earning $1m for the fight.