Wladimir Klitschko retained his IBF, WBO and Ring heavyweight titles with a brutal 12th-round knockout of American Eddie Chambers.

The Ukrainian, who along with brother Vitali is expected to fight Britain's WBA champion David Haye at some point, was never in danger of failing to keep hold of his belts against an opponent dwarfed in terms of size and quality.

Klitschko looked to be cruising towards a pedestrian but lop-sided points win until the closing seconds when, with the final bell five seconds away, a relatively unspectacular left hook snapped an exhausted Chambers' head to the side and left him a crumpled mess hanging over the bottom rope, clearly out for the count.

Klitschko, boasting a significant height and reach advantage over the baby-faced Chambers, dictated with the jab but did not have it all his own way in Dusseldorf. Indeed, midway through the first as the fighters went to clinch, Chambers bent forward and lifted the veteran in the air.

Chambers was pushing his luck and repeated the trick in the second round, going a step further by deliberately dumping Klitschko on the floor.

Klitschko had his revenge though, as Chambers' legs turned to jelly after a trademark right hand crashed into his exposed face. However, the American held on to see out the round and claim a minute's respite.

A better third for Chambers was still clearly won by the 'home' fighter, with the challenger's handspeed not matched by his footwork.

The unimaginative jab and straight right combination was as effective as usual for Klitschko but Chambers enjoyed occasional success, a left hook-right hand landing in the fourth but representing his only success.

That pattern continued into the sixth round, Chambers - marked up around the left eye - drawing a scolding from his corner for his passive performance. To his credit, he threw the left hook whenever an opportunity presented itself.

Klitschko did what he does best in the seventh, throwing multiple jabs followed by the piercing straight right. Chambers' defence was credible and his appetite for the fight apparent but there remained an air of futility to his cause.

A split in one of Chambers' gloves meant it needed to be replaced before the 10th - to the crowd's ire - and when the round got under way it was more of the same with the challenger reluctant to throw caution to the wind.

Even Klitschko's trainer Emmanuel Steward was frustrated, berating his charge for a lack of aggression.

In the final round he pushed for a stoppage and landed some good shots. Chambers handled them all well until the closing seconds, when Chambers took a left hand which knocked him clean out until he was able to sit after a couple of minutes.

On the same bill in Germany, Michael Sprott stopped Werner Kreiskott in just 54 seconds of the opening round and is now expected to meet Audley Harrison for the vacant European heavyweight title on April 9 at London's Alexandra Palace.

Sprott (32-14), a sparring partner of Klitschko, immediately wobbled the German journeyman with a right hand.

Kreiskott managed to partially blocked 35-year-old Sprott's follow-up attack, but another right got through which prompted the referee to step in.