HAMBURG – Boxing legend Mike Tyson is backing Wladimir Klitschko to knock-out Britain's David Haye in Saturday's heavyweight unification bout and says the brash Brit lacks the fire-power to claim victory.

Klitschko, 35, the IBF and WBO heavyweight champion, takes on WBA title-holder David Haye in Hamburg and boxing legend Tyson says the Ukrainian can knock the Brit out inside three rounds.

"David has never shown the punching power to force a guy of the caliber of Klitschko into reverse gear," Tyson, a former WBA, WBC and IBF champion, told German television channel RTL.

"We know that David Haye does not hit hard enough to get the respect of Wladimir Klitschko.

"I don't say this to disrespect Haye, but as an objective observer.

"I must say, this is a two or three-round fight."

Tyson lost his last title bout to Britain's Lennox Lewis in June 2002, but at the peak of his career in the late 1980s, he held three of the four major belts.