Wladimir Klitschko defended his WBO and IBF world heavyweight titles by stopping the previously unbeaten Ruslan Chagaev with a 10th-round TKO.
Klitschko, who had been due to meet Britain's David Haye on Saturday, dominated throughout and had his opponent down in the second round.
The Ukrainian then cut Chagaev above the left eye in the sixth.
And after three more rounds of punishment, Chagaev's corner pulled their man from the fight.
It was a classy performance from 33-year-old Klitschko with the fight being held in front of 61,000 fans at Schalke O4 FC's Veltins Arena in Gelsenkirchen, the biggest boxing audience in Germany in 70 years.
Now he (Haye) has to get in line and earn his chance to fight for the world title. He has to do that with his hands and not his mouth
Chagaev, who had his fight with joint WBA champion Nikolay Valuev called off last month because of health worries, was drafted in as a late replacement for Haye, but was outclassed throughout.
Haye withdrew earlier this month after sustaining a back injury in training.
And Klitschko hinted after the fight that the pair could still meet, although the 28-year-old former cruiserweight king would have to wait his turn.
"I was really upset that David Haye wasn't able to fight because I wanted to punish him badly," said Klitschko.
"Personally I'm very upset about David Haye. Because of him I didn't fight in March or April when he promised to deliver Stamford Bridge as a venue. But he didn't deliver.
"He then asked me to postpone this fight for two weeks because of his bad back and then changed it to four weeks. I cannot take this guy seriously.
"Now he has to get in line and earn his chance to fight for the world title. He has to do that with his hands and not his mouth.
"We'll get it on either way and I will knock him out in the 12th as I've said before."
The towering Ukrainian dominated from the first bell, rocking Chagaev with a powerful straight right.
Another straight right floored Chagaev in the second, but the Uzbekistan-born fighter cleared his head to make it through the round.
Klitschko used his superior reach to his advantage, using the left jab, straight right hook combination, to break through Chagaev's flimsy defence.
He rocked Chagaev in the fifth with another left-right combination and after Klitschko cut his opponent in the sixth, the fight was all but over.
To his credit Chagaev held on until the ninth, but after taking another beating his corner pulled him from the fight at the end of round.
It was Chagaev's first defeat in 27 fights, while Klitschko moves onto a record of 56 wins with 47 knockouts and just three defeats.
Klitschko now intends to meet joint WBA champion Nikolai Valuev, before a potential showdown with Haye.
"For me Chagaev is the best fighter in this weight division behind my brother (WBC champion Vitali) and I," said Klitschko.
"This is the first time he has lost and he is a very good fighter.
"Every punch in this fight was important. Now I want to fight for the WBA belt and I promise you I will be back here again."