Conor McGregor became embroiled in an angry exchange with referee Marc Goddard after leaping into the octagon to celebrate team-mate Charlie Ward's defeat of John Redmond at the 3 Arena in Dublin.
Ward took the fight, part of the Bellator 187 event, with a huge left-hander in the first round prompting the watching McGregor to gatecrash the celebrations.
The Dubliner, who was not involved with Ward's corner team or affiliated in any way with the event, took it upon himself to climb into the ring and charge at Ward in celebration before officials tried to calm him down.
When Goddard attempted to pull McGregor away, he reacted furiously, pushing the referee and screaming insults. It resulted in ugly scenes.
The prone Redmond, who was still being treated by medical staff following the stoppage when McGregor entered the ring, remained on his knees throughout the incident and at one stage, McGregor appeared to knock an official into him, knocking his fellow Dublin fighter off balance.
It's the second time in a month that McGregor has been involved himself in a fracas with Goddard.
At UFC Fight Night 118 in Gdansk, Poland, he left his seat as a spectator to give instructions to team-mate Artem Lobov.
Goddard was forced to stop the fight and order McGregor back to his seat as he wasn't part of Lobov's corner team.
McGregor, who was beaten by Floyd Mayweather in a boxing match in August, has not fought in the UFC since stopping Eddie Alvarez to capture the 155lb crown in November last year.