UFC 186 requires a new main event after bantamweight champion TJ Dillashaw suffered a broken rib in training that will keep him from his intended title rematch with Renan Barao on April 25th in Montreal, Canada.

Dillashaw shocked Barao at UFC 173 in May of last year when he dominated the reigning champ at the time before putting an end to his long unbeaten run by fifth round TKO.

This isn’t the first time a rematch between the two has been cancelled. A second fight had originally been planned for UFC 177 in September of last year, but weight cutting issues forced Barao out just hours before they were set to step on the scale and so Dillashaw was left facing ultra-late replacement Joe Soto who he would go on to defeat by KO.

For his part, Barao has since got back to winning ways courtesy of a submission victory against Mitch Gagnon at the tail end of last year.

At this stage the UFC have not decided whether they will keep Barao on the UFC 186 card. They do however have another title fight already scheduled for the event which could now serve as the headliner, with flyweight champion Demetrious Johnson going up against Kyoji Horiguchi.

That’s not a fight that’s likely to pull in many pay-per-view buys though, so if that’s how the card proceeds it will be a significant blow to the UFC after a strong start to 2015 so far.