Lennox Lewis has taken a large pay-cut to fight his No 1 challenger Vitali Klitschko on 21 June at the Staples Centre in Los Angeles.
Lewis was due to meet Canada's Kirk Johnson but he withdrew last Friday with a damaged pectoral muscle and at the time Klitschko, who was due to fight on the same night, was mentioned as a possible opponent, but dismissed.
The plan before last Friday's withdrawal of Johnson was for Lewis to fight Klitschko this November in Las Vegas in what would have been an enormous pay-per-view event in America.
Lewis will be taking a pay-cut for fighting Klitschko because his purse of $5m (£3m) for the Johnson fight will remain. The figure is short of the $12m that was suggested as a possible fee for fighting Klitschko in November.
Klitschko, 31, has lost just once in 33 fights and has stopped or knocked out 31 of the 32 men he has beaten and is the leading contender for both the World Boxing Council and World Boxing Association heavyweight titles. He is 6ft 7in and weighs nearly 18st and is possibly the most dangerous heavyweight, other than Lewis, on the planet.
"I'm prepared to take the pay-cut for this fight because I know that I will knock out Vitali,'' Lewis said.