Klitschko (r) was vastly superior to Peter in Frankfurt
Wladimir Klitschko easily retained his WBO and IBF world heavyweight titles with a 10th-round stoppage of Samuel Peter in Frankfurt on Saturday.
The Ukrainian controlled what was largely an unsightly slug-fest.
And after wearing Peter down, Klitschko finally floored the Nigerian as the referee belatedly halted the bout.
"He took a lot of punishment and fought until the end," said Klitschko. "But from round two, it was clear that his game plan wasn't working.
Peter, a former WBC champion in the division, had sent Klitschko to the canvas three times when the pair met in 2005.
Peter eventually lost that fight on points but Saturday's encounter in Germany - the adopted country of Klitschko and WBC champion brother Vitali - was quite a different night's boxing.
The 30-year-old was the second choice for the fight after Russia's Alexander Povetkin failed to show up for a pre-fight news conference because of a sinus problem, prompting the IBF to order Klitschko's management to find a new opponent.
It looked ominous for Peter early on when his eyes began to swell and, with his vision increasingly impaired, his aim grew wilder by each round.
He did manage to land one decent right hand in the fifth but, by the sixth and seventh, Klitschko's left hooks and right-hand jabs were really beginning to tell.
Warned by his corner at the end of the ninth that he was in danger of going the distance with Peter, Klitschko finished off his opponent with a flurry of blows to the head in the next.
A bloodied Peter crashed to the floor with one minute and 22 seconds of the round remaining, leaving referee Robert Byrd no option but to signal the end of the fight to the delight of 40,000 adoring Klitschko fans at the Frankfurt Arena.
The hollow victory, Klitschko's 55th in 58 bouts and 49th by knockout, is likely to prompt renewed calls for a unification fight with WBA champion David Haye.
Haye will make the second defence of his crown against fellow Briton and 2000 Olympic gold medallist Audley Harrison at the MEN Arena in Manchester on 13 November.