WBN has been informed that Josh Warrington suffered an injury and will not be able to compete in a spring clash with Kid Galahad.
The IBF featherweight champion was ordered to face his mandatory challenger. Promoter Frank Warren subsequently won the rights to stage the fight.
Warren was aiming to take the show to Leeds in May. Warrington now needs more time to recover.
That leaves Galahad with a tough decision to make regarding a potential warm-up contest beforehand.
Warrington won the title with a superb victory over Lee Selby. The Leeds United fan followed it up with another exceptional win when beating Carl Frampton.
An underdog for both clashes, Warrington proved he had what it takes to compete at the top level twice in succession.
This earned the warrior a WBN Fighter of the Year 2018 nomination and plenty of votes into the bargain.
The award was eventually won by Tyson Fury on the back of his performance and comeback against Deontay Wilder.
Despite calls for Warrington and Frampton to rematch, the International Boxing Federation pushed through their number one challenger.
There was also talk of Warrington making an appearance abroad at some stage, although the Galahad encounter blocked those plans.
Leo Santa Cruz and Gary Russell Jr. have both been in the crosshairs of Warrington for a unification.
For now, Warrington must focus on taking care of stipulated duties with Galahad in order to keep those dreams alive.
Galahad has earned his spot by amassing an impressive 26-0 record as a pro. The likes of Toka Kahn Clary, Irving Berry and Jose Cayetano have been defeated along the way.
Sheffield-based Galahad, who trains under Dominic Ingle, is now forced to wait for his chance once again.
Rescheduling of the bout should see Warrington v Galahad moved to the summer. The First Direct Arena in Leeds is the favorite to host.