Carl Frampton has been ordered to fight Guillermo Rigondeaux by July 27 to avoid being stripped of his WBA super-bantamweight title.
The Belfast fighter (22-0-KO14) added the belt to his IBF strap with a split decision win over Scott Quigg.
In the post-fight press conference, Frampton's manager Barry McGuigan appeared to rule out the Cuban as a possible opponent, saying: "He's amazing on the back foot but he's negative. What do we gain by fighting him?"
But the WBA has made Rigondeaux (16-0-KO10) it's mandatory challenger, despite stripping him of the title last year due to inactivity and promoting Quigg from interim to full champion status.
The governing body says unbeaten Rigondeaux's "impressive record and accomplishments" mean that he must be Frampton's next opponent.
"Frampton, Rigondeaux, and their respective teams have been notified that they must fight on or before 27 July 2016," said the WBA on it's website.
The statement added that the WBA was "honoured" to have Frampton as its champion.
"We congratulate him on a performance that was as intelligent as it was effective."
The Cuban, who was also stripped of his WBO world title, fights in Britain later this month when he takes on British champion Jazza Dickens in Liverpool on March 12.