The undisputed world cruiserweight champion was forced to call off his fight against Carlos Takam because of a biceps injury.
Usyk, 32, was due to face 38-year-old Takam in Maryland on 25 May, in what would've been his first fight in the heavyweight division.
The Ukrainian, though, had to cancel the fight after sustaining the above mentioned injury in training.
According to promoter Eddie Hearn, the fight has been postponed with further announcements to be made shortly.
Usyk decided to move up a weight class after becoming the first boxer to hold all four world titles at cruiserweight. The 2012 Olympic champion is unbeaten in 16 professionals fight, with 12 of his wins coming by knock-out.
Takam (36-5-1), returned to winning ways against Senad Gashi, following successive defeats to Anthony Joshua and Derek Chisora.