Lightweight world champion Jorge Linares and mandatory challenger Luke Campbell, whose camps have already been in talks, likely will meet next after they were ordered to face each other.

Linares is penciled in for a Sept. 23 title defense in the main event of an HBO-televised card that likely will take place in Southern California, and Golden Boy Promotions, Linares' promoter, has been in talks with Campbell promoter Eddie Hearn of Matchroom Boxing in an effort to make the bout.

What could speed up those talks is the WBA's order for them to meet next because Linares' mandatory defense is due. The sanctioning body sent both camps a letter Friday calling for the sides to negotiate the bout. They have 30 days to make a deal, or a purse bid will be ordered.

Linares (42-3, 27 KOs), 31, of Venezuela, who was stripped of the WBC's 135-pound title while he was dealing with a hand injury in 2016, returned from an 11-month layoff and outpointed Anthony Crolla on his turf in England to win the WBA's belt last September.

Then Linares easily outpointed Crolla in a rematch in March to retain the title.

Linares would make his second defense against Campbell, a 29-year-old southpaw from England. Campbell (17-1, 14 KOs), a 2012 Olympic gold medalist, became Linares' mandatory challenger by virtue of a ninth-round knockout of former world titleholder Darleys Perez in their title elimination fight on the undercard of the Anthony Joshua-Wladimir Klitschko heavyweight title fight on April 29 at Wembley Stadium in London.