Rees was scheduled to meet WBU champion Kevin Lear on Saturday 15 February at the Wembley Conference Centre.
But a shoulder injury incurred during training by Lear has now delayed what promises to be an explosive match-up between two undefeated talents.
Their fight will now be re-scheduled to take place at a later date this year once Lear's injury has fully healed.
Newbridge-based Rees, who is trained by Enzo Calzaghe - father and coach of WBO super-middleweight champion Joe - will remain on the bill and compete in a non-title fight against a yet to be named opponent.
But top billing will now be a final eliminator for the British lightweight title and Southern Area Championship between Harlow¿s Steve Murray and Graham Earl of Luton.
"Gavin will still fight Lear but when he's fit," Calzaghe Snr told the South Wales Argus.
"
To say I am gutted is an understatement
"
WBU super-featherweight champion Kevin Lear
"He is gutted it's off but there's not much we can do about it because we can't defy medical grounds. It's just one of those things.
"Gavin will still box next Saturday - but I think we'll call it a warm-up for the Lear fight, because Gavin is confident he can topple him.
A devastated Lear added: "To say I am gutted is an understatement.
"All my preparations were going fantastically, probably the best they have ever been for a fight and then this happens.
"The injury is an old one from my amateur days that I thought had gone away.
"Unfortunately in my last sparring session it resurfaced when I landed with a right hand that jolted my shoulder upwards and I dropped from the pain."