Liverpool fighter Darren Till was knocked out by Jorge Masvidal in the second round of their welterweight contest at UFC London – but the American's victory was overshadowed by a backstage altercation.
After the fight, footage emerged of Masvidal breaking off from an interview to confront Jamaican-born Birmingham fighter Leon Edwards, with the pair trading blows.
In an ESPN video posted to Twitter, Masvidal could be heard saying, "Come over here, say that to my face", before security teams were seen to intervene to break up the fighters and the footage cut off.
A longer video posted on ESPN's MMA YouTube page showed Edwards with a cut under his left eye.
Later, Masvidal retweeted a video of an interview with the sports broadcaster, where he explained the incident.
He said: "As I walk up to him, I've got my hands behind my back to signal I'm not coming here for problems. But he put his hands up like this. It's on video, and he walks towards me.
"Well, where I'm from, if you do that, you're going to punch me in the face. That's not going to happen.
"So I gave him the three piece with the soda, and then just glide out of there."
Beforehand in the octagon, 26-year-old Till was headlining at the O2 and back in action since suffering a first defeat as a professional to UFC welterweight champion Tyron Woodley last September in Dallas.
However, Till, third in the UFC rankings and seeking another crack at the title belt against newly crowned champion Kamaru Usman, was put down by a strong left-hand shot from veteran Masvidal.
Till spent the early part of his professional career in Brazil, with Saturday's main event contest only a second fight in England for the Merseysider on an evening when Michael Bisping was entered into the Hall of Fame.
Following a raucous welcome by the sell-out crowd on the banks of the Thames, Masvidal landed a low kick during the opening exchanges with Till then landing a jab which put the American down.
However, Masvidal, who boasted a record of 32 wins and 13 losses coming into the octagon on Saturday night, then delivered a viscous left which rocked Till and sent the Englishman to the floor, before he was struck again ahead of the contest being ended by referee Marc Goddard.
Following treatment by medical staff, which looked to include oxygen, Till was brought round before returning to his dressing room.
Masvidal paid tribute to Till during his post-fight victory speech.
"Whether you booed or cheered, this is mindblowing – thank you," he said on BT Sport.
"I couldn't have asked for a better opponent. He's got so much further to go, he's a young tiger right now. I'm 34 and near the end of my career."
Appearing to target a title shot himself, the American added: "Back to business, I need that belt around my waist.
"He's only lost one fight before this so that shows that I deserve my opportunity. I need that belt around my waist.
"First round was definitely his, I couldn't handle his timing. By the second, I settled down and found my rhythm. I love this sport. I'm here to fight the best in the world and I want the champion right now."
Elsewhere on the under card, Edwards had earlier taken a split decision in his welterweight bout against Gunnar Nelson, who is Conor McGregor's training partner.
UFC executive David Shaw told a press conference the incident between Edwards and Masvidal would be reviewed before deciding whether any sanctions should be handed out.
"Too early to tell, we'll review it. Dana (White, UFC president) is already looking at it. We'll review everything, all the details, over the weekend, Monday morning, and take next steps from there," he said.
London bantamweight Nathaniel Wood, meanwhile, defeated Jose Alberto Quinonez via a second-round submission for his eighth MMA win in a row.
