Ukrainian Iago Kiladze hit out literally at the referee following his defeat to heavyweight rival Viktor Faust in Florida, only for the official to respond by laughing.
Fighting on the undercard of the Luiz Oriz v Charles Martin clash, Kiladze and his countryman had put on an epic round and a half as they shared five knockdowns in the early going, with the 35-year-old going down twice early on and Faust also hitting the deck.
Both floored each other again early in the second round but then, with the crowd going wild, referee Samuel Burgos spoilt the fun by stepping in to stop the bout after Kiladze appeared to stagger sideways.
The decision drew boos from some fans with even Faust, 29, looking somewhat bemused as the final bell was called.
Kiladze, however, then let frustration boil over as he reacted by throwing a right hand at Burgos, striking him on the left arm and then inadvertently on the chin as his arm bounced up following the blow.
“You cannot do this,” shouted one commentator after Kiladze landed the shot.
“That’s going to cost him money, You can’t do that, you can’t get violent with the referee.”
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To the credit of Burgos, he remained composed, cooly stepping out of range before proceeding to laugh his way through a post-fight interview, clearly able to see the funny side.
“Look, this is a man’s game, he’s frustrated, but I stand by my decision in terms of waving off the fight,” the official was quoted as saying afterwards.
A clip of the incident was posted on Twitter by @FTB_Vids_YT, and the majority of fans seemed to side with referee Burgos.