David Haye has agreed a deal to fight Nikolay Valuev for the WBA heavyweight title on November 7.
The British fighter is eight stone lighter and nine inches smaller than the 7ft 2in Russian champion.
Valuev has yet to be knocked down in his 16-year professional career and has lost once in 50 fights.
The announcement ends speculation about Haye's next opponent, after reports that he had agreed a bout with Vitali Klitschko.
David Haye tickets would be on sale soon."I am thrilled to announce that my dream of becoming world heavyweight champion will be realised on November 7, when I challenge the tallest and heaviest champion of all time, Nikolai Valuev," Haye said.
"David only needed a slingshot and a stone to flatten Goliath, and I'm convinced my right hand generates more power than a stone.
"When I dreamt about fighting for the heavyweight world title I knew the guy would be big, but not this big. It's a tall order but I am confident in my ability."
There was speculation Haye's next opponent would be Vitali Klitschko.
Haye had been scheduled to fight Klitschko's brother Wladimir in June but had to miss the bout because of a back injury.
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