UFC light heavyweight champion Jon Jones has injured his leg, forcing the postponement of his title fight with Daniel Cormier to Jan. 3.
The UFC announced the move Tuesday.
Jones (20-1) was scheduled to fight Cormier (15-0) at UFC 178 in Las Vegas on Sept. 27 in the mixed martial arts promotion's most anticipated event of the fall.
Instead, Jones and Cormier will headline UFC 182, the promotion's traditional year-end show in Las Vegas.
Jones is widely considered the top pound-for-pound fighter in MMA, while Cormier is an undefeated former Olympic wrestler. They generated major publicity for their bout last week when they scuffled during a promotional event in the MGM Grand casino lobby.
Flyweight champion Demetrious Johnson will fight Chris Cariaso in the new main event of UFC 178.