Oleksandr Usyk has been ordered to fight mandatory challenger Daniel Dubois, the WBA confirmed.
The Ukrainian defended his trio of heavyweight belts in a rematch with Anthony Joshua in August, then entering negotiations with Tyson Fury for a unification bout.
However, Usyk was unable to secure terms with Fury for a fight that would have crowned the first unified heavyweight champion since 2000, with the expectation being that Dubois would therefore be his next opponent.
On Monday, the WBA wrote on Twitter: "The WBA Championships Committee ordered the bout between Heavyweight Super Champion Oleksandr Usyk and Daniel Dubois.
"The organisation sent the communication to the parties today with a 30-day negotiation period starting on April 4 and ending on May 2."
Usyk is the holder of the WBA, WBO and IBF titles and, with the rotational agreement between the government bodies, Dubois is the first in line for his shot.
The Brit secured his position last year with victory over Trevor Bryan to claim the WBA 'regular' title, and successfully defended it against Kevin Lerena.