Lennox Lewis has until 1 March to decide whether to defend his heavyweight world title in a rematch
with Vitali Klitschko.
Lewis was behind when cuts halted Klitschko's challenge
The World Boxing Council said if Lewis opts not to fight the Russian, he will be stripped of his title.
The top two contenders, Klitschko and Corrie Sanders of South Africa, would then fight for the vacant crown.
WBC president Jose Sulaiman also stated on the WBC website that Lewis and Klitschko must agree terms in February.
If they do not, the fight would go to a purse bid on 15 March.
Lewis, 38, has been secretive about his plans, hinting that he
may retire instead of fighting Klitschko again.
He won the first bout last June in Los Angeles, when the challenger was stopped by bad cuts after leading on all three scorecards for six rounds.
Lewis' trainer Emmanuel Steward has said he believes the champion will either fight Klitschko again or retire.
"It's the only fight he really wants to clean up the situation but I don't think he knows what he'll do."