Wladimir Klitschko stopped Danell Nicholson in the fourth round here on Saturday in the second fight on the comeback trail for the former WBO champion.
The referee waved off the fight with 1min 16sec left in the fourth round as Klitschko battered the American on the ropes after knocking him down seconds earlier.
Klitschko, 27, is the younger of the two fighting Ukrainian brothers, with Vitali, the elder, also a top heavyweight contender.
"It wasn't easy, but he moved a lot and it isn't easy to hit a moving target," said Klitschko, who has won 43 of his 45 bouts with 39 knock-outs. "But the important thing is it will continue for me and Vitali next year."
The two big brothers have made no secret of their goal to own heavyweight titles at the same time. But Wladimir has to redeem himself first after losing his WBO title in stunning style in March, when he was punished in two rounds by the South African Corrie Sanders.
Klitschko began his comeback in August, knocking out the hopelessly overmatched Argentine fighter Fabio Moli in 97 seconds, but his corner admitted before taking on Nicholson that his confidence had taken a big hit from the Sanders fight.
"No fighter gets knocked out for the first time in his career without losing confidence," his co-trainer, Freddie Roach, said. "I hope Nicholson stands up for a few rounds, because it's the only way he will get it back."
Nicholson, with a 42-5 record and 32 knock-outs, tied up the 6ft 7in Klitschko at every opportunity. He was penalised a point for holding in the second and warned again in the third.
"It wasn't working. When it isn't working you try some things," Nicholson said.
The end came quickly - Klitschko knocked Nicholson into the ropes with a left hook in the fourth, then followed with some combinations. After Nicholson had got back to his feet, the Ukrainian sent him into the ropes again, with a short right to the head appearing to finish him after Nicholson had absorbed several blows.
"It wasn't an easy fight - but it was a good performance. His next fight will be for a world title," said Vitali Klitschko, who was in his brother's corner as usual.