Klitschko (right) could next fight Britain's David Haye
Vitali Klitschko retained his WBC heavyweight title with a 10th-round stoppage of Albert Sosnowski in Gelsenkirchen, Germany.
Sosnowski held his own until the ninth when he needed the bell to save him from a furious Klitschko onslaught.
And the Ukrainian ended the contest in the next round with a huge right that sent the Pole crashing to the canvas.
Klitschko said his next opponent is likely to be Britain's WBA heavyweight champion David Haye or Ruslan Chagaev.
"I was in good form, Sosnowski was younger than me, but people saw that I did well against him," reflected Klitschko, who at 38 was seven years his opponent's senior.
"He did everything to win this fight, but my experience got me through."
That seemed a fair assessment from the Ukrainian who physically did not look at his peak against the European heavyweight champion.
When Sosnowski connected with the Ukrainian's chin in the fourth, it seemed to jolt Klitschko into life, and some telling combinations in the fifth and sixth saw him regain the ascendancy.
Klitschko seemed to tire somewhat when Sosnowski, 13 centimetres shorter and 23 pounds lighter than the champion, resumed his attack in the seventh and eighth rounds.
However, when Klitschko pinned Sosnowski to the ropes with a flurry of punches in the ninth, there looked like being only one winner.
And, with 29 seconds left of the 10th remaining, a devastating right from the Ukrainian opened a cut above Sosnowski's left eye and floored him as Klitschko picked up the 40th win win of his career with his 38th knockout.
"I am a bit disappointed, because I thought I had a good chance of winning this fight," said Sosnowski.
"I am okay now, it was a hard punch, but I was also quite tired and I just didn't have the energy to get up.
"I am grateful for this fight and I hope to have another shot at the title in future."