Vitali Klitschko has accused David Haye of overstepping the mark after the British boxer was shown in a mock-up photo with the decapitated head of his brother Wladimir.
Wladimir proved he is the top heavyweight on the globe with a convincing win over Hasim Rahman in front of the Setanta cameras on Saturday night but a row has raged after the fight in Mannheim.
Vitali, who is set to take Haye on in London next June, has threatened to exact revenge for the picture as he will enter the ring with a "cold heart".
"I admit that I was shocked with what I saw in the Men’s Health magazine and my wife even felt unwell," he told the Russian media.
"It is difficult to describe my feelings at the moment. There is David Haye on the photo laughing with the head of my brother.
"I came to David of course and said that it was too blatant and that he overstepped the mark. But, as a response, I got the words that he would beat my brother and then me.
"I will reply for my brother. He must pay for this photo. I seldom feel inclined to fight but, this time, I will enter the ring with a cold heart.
"You know lots of people said that they would knock my brother and me out. But it is well known what happened to them, the same would happen with Haye."