Mikkel Kessler has been forced to withdraw from his April 14 super-middleweight showdown with Robert Stieglitz.
It is the second time the Dane, who is nursing a hand injury, has postponed a fight with the WBO champion.
Kessler said that he will return to action a month later in front of his home fans against an opponent yet to be announced.
"I hate to keep my fans waiting and I am really sorry about the delay," said the 33-year-old.
"As a boxer, my fists are my biggest weapon. To fight and to win at the highest level, I need my hand to be fully recovered.
"Unfortunately, the April 14 date comes just a little too early but I will be ready on May 19. I have kept my shape and can't wait to be fighting again in front of my Danish fans."
It is believed that the WBO will now order Stieglitz to face mandatory challenger George Groves.
