WATCH: UFC’s Grant Dawson delivers BRUTAL HAMMERFIST KO in LAST SECOND of Las Vegas fight as fans blast referee

Grant Dawson was awarded a Performance of the Night bonus for his savage exploits at UFC Vegas 22 on Saturday night as he landed a buzzer-beating KO in his lightweight contest with Brazilian rival Leonardo Santos.

With the bout set to head to the scorecards, the 27-year-old Dawson didn’t want to leave his fate in the hands of the judges and got the job done within three rounds.

Laying a barrage of brutal hammerfist blows down on Santos that caused his foe’s mouthguard to fly out, the referee stepped in to stop the ground-and-pound pummeling with just one second to spare.

Though some dubbed the feat “unreal”, fans in general were less impressed by the officiating. 

“Awful reffing, he was out after [the] first one landed clean, I could tell on my couch and he took three more clean [shots] for no reason. Shaking my head,” decried one Twitter user. 

“Wtf was the ref doing? At least two big shots after he was out,” questioned another in agreement, as someone else said: “Yeah just jump in whenever you’re ready ref.”

“Shocking from the ref. Truly shocking,” it was also said.  

The victory improved former 'Dana White's Contender Series' star Dawson to 17-1 in professional MMA, and extended his winning streak to eight.  

He used his post-fight interview to call out US veteran Clay Guida. 

The UFC's 155lbs fold is notoriously infested with threats, but the statement win from Dawson as he stepped up to the division surely gave matchmakers another name to think about in the mix.  

For Santos, meanwhile, it was remarkably a first defeat in a decade, and snapped an unbeaten run in the UFC dating back to 2013, during which time he had won seven and drawn one of his eight contests in the octagon before tasting a rare loss against Dawson.