McGregor suffered the injury during the first round of their trilogy bout in Las Vegas with Poirier getting the win via doctor’s stoppage with the Irishman unable to continue.
The build-up to the fight was marred by McGregor seriously threatening his opponent’s safety and he continued his tirade against Poirier in his post-match interview, this time including references to the American’s wife.
Poirier (27-7 MMA) addressed the comments after the contest with UFC commentator Joe Rogan in his post-fight interview, saying: “I can take, you know, the trash talk. There’s no holds barred with the trash talk, right?
“But murder is something you don’t clown around about, there’s no coming back from that, and this guy was saying he was gonna murder me and all kinds of stuff. He was telling me he was gonna kill me tomorrow. I’m gonna leave here in a coffin.
“You don’t talk like that to people, man. I hope he gets home safe to his beautiful family. But, you know, this guy is a dirtbag. Karma is not a b****, she’s a mirror, and this guy said the wrong s***.”
The fight itself saw McGregor start aggressively by targeting Poirier with leg kicks, but the American quickly capitalised after seeming to hear McGregor’s leg crack during one exchange.
Poirier took his opponent to the ground, where he dominated before the fighters returned to their feet.
Both swung and missed and McGregor stepped back before his leg collapsed beneath him, sparking speculation he may have suffered a bone fracture.
McGregor somehow survived until the end of the round when the bout was stopped.
“I felt something, for sure,” said Poirier. “He fractured it on one of the kicks at the beginning of the fight, and then he broke it as he twisted throwing a punch. I checked the kick, he was kicking very hard.
“You never want to get a win that way, but what happened was the result of checking a kick. I’m more than sure of it. He got what he had coming to him.”
Former featherweight and lightweight champion McGregor (22-6 MMA), who left the arena on a stretcher and was immediately taken to hospital, disagreed with Poirier’s theory.
“There was no checking. I was boxing the bleeding head off, kicking the bleeding leg off,” said McGregor.
“This is not over. If I have to take it outside, let’s take it outside.”
UFC president Dana White condemned McGregor’s comments both before and after the fight, before dropping a strong hint that the pair could meet for a fourth time when McGregor has recovered.
“I don’t like that, that’s not good,” said White. “Leave people’s families and wives and all that stuff out of it. Family has nothing to do with it.
“It sucks for it to end that way, it’s brutal, it’s not the way you want to see fights end. It’s a break of the lower tibia in his left shin and he will go into surgery tomorrow (Sunday).
“The fight didn’t get finished. We’ll see how this whole thing plays out. Who knows how long Conor is out? Poirier will do his thing until Conor is ready.
“Dustin Poirier will fight for the title (against lightweight champion Charles Oliveira) and when Conor is healed and ready to go, you do the rematch, I guess.”