Jose Aldo, the
A UFC spokesman said Thursday "the only information we have is that [Aldo] is out of the fight." A Brazilian report indicated Aldo suffered a shoulder and back injury, but the UFC could not confirm that.
Aldo (24-1) has been champion since April 2011 and has successfully defended the belt five times, against challengers including Mendes, former lightweight champion Frankie Edgar and Kenny Florian.
Mendes (16-1) has won five consecutive fights, including three by first-round knockout, to earn the rematch.
The UFC hasn't announced a replacement main event and the timing of the injury could threaten whether the card can even proceed on the scheduled date.