Fight fans have called for the sacking of referee Dan Miragliotta after he missed a tap out from Charles Oliveira at UFC 218.
The horror mistake led to Oliveira getting absolutely pummelled on the ground by his opponent Paul Felder.
Vision of the fight shows Oliveira tapping the shoulder of his opponent, with Felder even pausing for a moment in anticipation of referee Miragliotta calling off the bout.
But without the signal of the referee, Felder unfortunately had to go on with the fight, throwing down a series of hard elbows into the head of the defeated Oliveira.
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"You know how it is in there," Felder said.
"Maybe he’s trying to move out of it, I just kept going. But I could feel him tap, yeah."
It was a horrible incident for Oliveira, who was unable to immediately get to his feet after the battering.
Fight fans took to Twitter to condemn Miragliotta's mistake.
Watch the incident in the video at the top of the page.
It was just one of a number of big moments from UFC 218.