WBA, WBO and IBF heavyweight champion Wladimir Klitschko has hit back at his next opponent Tyson Fury, saying his brain is the 'size of a squirrel or walnut'.
The delayed fight will take place in Dusseldorf on November 28 and much of the elongated lead-up to the fight has been taken up by a barrage of verbal attacks towards Klitschko.
In an interview with the Daily Mail, Fury expressed strong views about abortion and homosexuality.
The 27-year-old also called Klitschko - boasting 64 wins from 67 professional fights - a "devil worshiper".
Ukrainian Klitschko, who forced a five-week postponement of the bout due to a calf injury, responded in a news conference, telling reporters: "Surprisingly when I head those comments, it shows that Tyson's brain is the size of a squirrel or a walnut by making comments like that.
"So it doesn't make me feel more aggressive, it doesn't make me feel more different. It's just his nature."
Klitschko, 39, added: "We live, thank God, in a democratic world and people have a right to an opinion. But people need to respect each other.
"As for calling me a devil-worshipper [for liking magic tricks], that's just stupid. When Tyson Fury starts working in the circus, he'll be working with some amazing magicians.
"And if he still believes it's magic, well, between you and me, it's not magic at all but just tricks. But I will do some magic on Tyson Fury in Dusseldorf - I'll knock him out and make him disappear from boxing."
Klitschko also questioned Fury, who labelled the world champion as a "boring old man".
"So I'm an old man? And it's impossible for a 27-year-old to lose against an old man? Then he trains like crazy. So I am asking myself, there is a controversy by polarity. Because he is changing his mind," said Klitschko.
"On one side he admires me and on another side he says I'm basically nothing. On one side he admires me and then says he's overrated. Then he says that 'Hall of famer' Lenox Lewis hasn't done boxing a thing and then before he was looking up to him.
"So there is a lot of things that doesn't make sense to follow because you're going to get lost and it doesn't make sense because you're not getting anything for your life reading it and following it. There is a lot of controversy as I said."