UFC fans stunned by 'brutal' comment Mark Zuckerberg made to Justin Gaethje behind the scenes at UFC 313

UFC fans have been left stunned by Mark Zuckerberg's 'brutal' comment to Justin Gaethje backstage at UFC 313.

Gaethje entered his lightweight clash against Rafael Fiziev coming off a loss following his crushing knockout defeat to Max Holloway at UFC 300 last summer.

Gaethje and Holloway threw down in the middle of the Octagon before the Hawaiian landed a devastating shot that put his opponent to sleep.

But 'The Highlight' returned to the win column at UFC 313, beating Fiziev, who replaced Dan Hooker on short notice, in a Fight of the Night battle.

He edged out his Azerbaijan foe on the judges' scorecards following a 15-minute war.

After his victory, Gaethje spoke to the media and embraced with his team and family, with his parents in attendance at the T-Mobile Arena.

He also bumped into Zuckerberg, who was sat front row alongside UFC CEO Dana White, as they were involved in an awkward exchange.

After shaking hands, Gaethje asked Zuckerberg: "You been to mine live before?"

To which the Meta chief replied: "Yeah... yeah this one was better than the last one."

The UFC star laughed off Zuckerberg's comment in a hilarious sequence.

Needless to say, Gaethje and Zuckerberg's conversation got fans online talking.

One X user wrote: "Brutal," while another said: "He’s so awkward."

A third added: "It seemed like he blurted it out lol. Justin took it gracefully."

Gaethje is hoping for another shot at UFC gold, with UFC commentator Jon Anik backing his case.

"He absolutely should fight Islam Makhachev for the title," Anik told Bloody Elbow. "I don’t know that he could’ve done more with this showcase, and sometimes decision wins could be better than finishes, and I think in this instance, had there been a quick knockout, I actually think this is more useful.

"Justin Gaethje is going to go in the Hall of Fame twice."