The astonishing footage above comes from the ongoing European Youth Boxing Championship in Zagreb, Croatia.
In the light heavyweight clash between Vido Loncar of Croatia and Algirdas Baniulis of Lithuania on Monday, Loncar had a simply incredible reaction to losing his match.
As you can see at 1:13 in the video above, Loncar knocks the referee to the mat with a quick combination before repeatedly unloading punches once the official is down. The fighter is then finally pulled away.
You can see the attack from another angle here:
Chaos then ensues. Loncar appears to run to the dressing room while being chased by a number of people.
Update: October 22 17:15 BST
Locar and his coaches have now been banned for life, the International Boxing Association have confirmed.
The referee in question, Maciej Dziurgot, had to be taken to hospital and Locar was also arrested by police.
President Ching-Kuo Wu said, as per The Guardian: "AIBA and the entire boxing family have zero tolerance for this sort of behaviour."
[YouTube, h/t Balls.ie]