Nikolai Valuev will fight John Ruiz for the vacant WBA heavyweight title before 31 August.
Ruslan Chagaev was forced to pull out of his mandatory title defence against Valuev on Saturday night after rupturing his Achilles' tendon in training last week and the WBA decided on Thursday that the two former champions will face each other.
'We wanted Nikolai Valuev to fight for the title as soon as possible,' Valuev's manager Chris Meyer said in a statement. 'We consider the WBA's decision a big success.'
The two sides will have until July 15 to find a solution as to who will stage the fight and if no agreement can be reached, a purse bid will be called.
Valuev, the WBA's top-ranked fighter, earned a 12-round majority decision in his only other meeting against Ruiz in December 2005.
Chagaev will have a chance to challenge the winner of this fight when he is healthy enough to return to the ring.
