The fight was stopped after the first-round bell when McGregor (22-6) was unable to continue. The biggest star in mixed martial arts never got up after falling to the canvas following a final-minute blow by Poirier (28-6), who will get the UFC's next lightweight title shot.

Poirier said he thought McGregor's leg broke when he checked one of McGregor's kicks earlier in the fight.

“I felt something, for sure,” Poirier said. “He fractured it on one of the kicks at the beginning of the fight, and then he broke it.”

Poirier was largely in control of the opening round, parrying McGregor's kicks and landing several strikes before getting control over McGregor on the ground. After a long stretch of punches and elbows on the prone McGregor, Poirier knocked him down one last time — and McGregor's ankle bent gruesomely as he fell.

McGregor was furious about the circumstances of his loss before he was carried from the cage.

“This is not over!” he shouted.

Poirier stopped McGregor in the second round when they met in Abu Dhabi last January, avenging his first-round knockout loss to McGregor in 2014. Poirier’s clear superiority in the fighters’ second bout made a third showdown seem questionable just six months later, but McGregor demanded the chance to fix his mistakes and Poirier accepted the massive paycheck that comes from sharing a cage with McGregor.