Liverpool super-middleweight Callum Smith will face Nieky Holzken in the World Boxing Series semi-final after Jurgen Brahmer withdrew with illness.
Germany's Brahmer, 39, has been suffering from flu and said "a fight in this state is out of the question".
Dutchman Holzken, 34, will go into the bout in Nuremberg, Germany, with 13 wins from as many fights.
"I am committed to fighting on Saturday and will fight whoever the WBSS puts in front of me," said Smith, 27.
"We got the call as we were boarding the plane (on Monday)."
Smith is unbeaten in his 23 professional bouts, with 22 victories in Great Britain and the other win in the United States.
The winner of the fight will face George Groves, who beat Chris Eubank Jr, in the super-middleweight final.
Groves suffered a suspected dislocated shoulder in the win over Eubank Jr, which puts his place in the WBBS final in doubt.
He says the date might have to be changed for him to recover for a final that "wouldn't be the same" without him.
"It would be a shame if Groves isn't in the final," Joe Gallagher, who trains Smith, told BBC Radio 5 live.
"We'd love George to make a speedy recovery and be ready for 2 June but I do feel common sense will prevail and they may have to reschedule it to July-August time."