Dustin Poirier said he knew he'd destroyed Conor McGregor when he looked down at his disfigured shin

• Dustin Poirier finished Conor McGregor after just five minutes of fighting.
• The American said he knew the fight was won when he saw McGregor's disfigured (and broken) leg.
• Even after defeat, McGregor continued to make death threats, Poirier claimed.

Dustin Poirier said he knew he'd destroyed Conor McGregor when he looked down at his disfigured shin after five minutes of fighting Saturday at the T-Mobile Arena in Las Vegas.

The American athlete had already beaten his lightweight rival once this year, finishing the Irishman in the second round of a wild fight at the Etihad Arena in Abu Dhabi.

Six months later, it was a case of repeat rather than revenge as Poirier closed the show at the end of the opening round as McGregor was in no fit state to continue.

He told reporters at a post-event press conference that he knew the fight was over before he sat on his stool for the one-minute break between rounds.

"When I was walking away, and he stayed down, I looked down at his shin and I saw the bone disfigured a little bit," said Poirier.

He claimed that the damage might have been done when he checked (blocked) one of McGregor's kicks earlier in the round.

"It's just weird it held together," he said. "Probably when he pivoted on that bone, that's when it separated or something."

The 32-year-old added: "I sit on the stool, and I forget who was it in my corner who came up to me and said, 'This is over'."

And it was. But rather than bury their three-fight rivalry with the 2-1 loss, McGregor continued to talk trash about Poirier's wife, Jolie, before issuing another death threat like he had done earlier in the week.

"Conor said some nasty stuff," Poirier told the media.

"Maybe when this behind-the-scenes for this fight airs, you'll see him on the ground still saying some real bad stuff."

Poirier said that, regardless of what's been said, he wouldn't wish serious harm on anybody, and he even prays for his welfare as well as his opponent's whenever he walks to the Octagon.

But though he has two knockout finishes over McGregor, against one knockout loss, in one of the highest-profile trilogies the UFC has ever booked, the rivalry is by no means over.

"We are going to fight again whether it's in the Octagon or the sidewalk," Poirier said.

He later added: "He was saying he was going to kill me, murder me, you don't say stuff like that.

"You don't wish that on anybody," he said.

"He was saying … he was still sitting on the ground, saying I'm going to kill you, putting his hand to his head like a gun. Chill out."

Poirier will now fight Charles Oliveira for the UFC title

As McGregor gets taken to hospital for surgery Sunday morning, the UFC boss Dana White will consider the next big lightweight match.

"Dustin Poirier will fight for the title," he said, confirming a championship bout between the Louisianan and Charles Oliveira.

"And when Conor's healed and ready to go, you do the rematch, I guess," White said.

Poirier is keen to take some time off from combat sport to reconnect with his wife and his young family, before preparing for that 155-pound title match later this year.

But should he win Oliveira's belt, and should McGregor make a full recovery, Poirier wants the Irishman to win before fighting for his title.

"He has to win some fights," he said. "But a guy like that goes out and starches somebody, he's right back in the top contender talk just because of his star power."