Wladimir Klitschko claims David Haye would have knocked out Tyson Fury had their twice-scrapped fight gone ahead.
Injuries twice forced Haye to pull out of a meeting with Fury, who fights for Klitschko's three world heavyweight titles on November 28.
Haye has been where Fury now stands, only to lose a one-sided contest to the Ukrainian in 2011.
But despite a wide points win that night and his insistence he is in for one of his most difficult challenges to date later this month, Klitschko says both Haye and up-and-coming Anthony Joshua would beat Fury.
"David Haye would have knocked out Tyson Fury if that fight had happened," he said at his Austrian training camp.
"I fought David Haye and I've sparred Joshua and can tell you David Haye would have knocked Tyson Fury out if he had taken that fight.
"It was not easy (when I fought) David Haye. Haye was fast with his hands and footwork, it was extremely complicated to hit him.
"Tyson Fury is not a power puncher. He does not have power behind his punches, is it with combinations that his opponents are TKO'd?
"Anthony Joshua is still raw but improved a lot so I think he would (beat Fury), yes. He would win that fight too."
Klitschko and Fury, who has 18 KOs on his unbeaten 24-fight record, first crossed paths five years ago when trainer Emanuel Steward brought the Mancunian to a training camp.
Fury claims he was denied the chance to spar the champion, but Klitschko said: "Emanuel was trying to protect him from crumbling mentally in the ring with a champion. He was way too raw.
"He would have been beaten up badly and that wouldn't have been good for his mental side, but I remember him as very nice kid back then. Very courteous and respectful."