Whittaker, the former UFC middleweight champion, wrote that he suffered an injury early in his training camp and won't be healed in time for the bout, which was set for June 11 in Singapore. He did not disclose any specifics about the injury.
"All this means is that I'll be competing a couple months later," Whittaker wrote. "When I get in that octagon next I'll be better than ever."
Vettori's manager, Ali Abdelaziz of Dominance MMA, told ESPN that Vettori is unlikely to remain on the UFC 275 card. On Twitter, Vettori has already called out fighters such as teammates Khamzat Chimaev and Darren Till. Vettori is a former UFC middleweight title challenger.
"We're back at this," Vettori wrote. "I think I'm the only 185er that can say that has never pulled out of a fight but anyway smash boys I'll get you back to back lets do it I'm willing to die just show."
ESPN has Whittaker ranked No. 2 and Vettori ranked No. 4 in the world at middleweight.