Colby Covington hit out at a "fake stoppage" by referee Marc Goddard after he fell to a fifth-round defeat to Kamaru Usman in the main event at UFC 245.
Usman retained his welterweight title in Las Vegas after a series of brutal shots in the final round, Goddard stepping in to call a halt to proceedings with Covington sent to the canvas as the Nigerian continued to aim strikes at his head.
Covington suffered a broken jaw but was angered by Goddard's decision and took to social media to air his frustration.
In a post on Twitter, former interim champion Covington wrote: "Normally people do their f****** in the bedroom, not the octagon @marcgoddard_uk!
"I go in there to kill or be killed. You robbed me of that. You robbed the people of a fair fight. You should be ashamed of yourself. Fake nut shot. Fake eye poke. Fake stoppage. Fake ref."
Normally people do their fucking in the bedroom, not the octagon @marcgoddard_uk! I go in there to kill or be killed. You robbed me of that. You robbed the people of a fair fight. You should be ashamed of yourself. Fake nut shot. Fake eye poke. Fake stoppage. Fake ref. #ufc245— Colby Covington (@ColbyCovMMA) December 15, 2019
The build-up to the bout was marked by a bitter war of words between Covington and Usman, who is on a 15-fight winning streak.
Usman, now 16-1 in his UFC career, said in his post-fight interview: "I heard all week, all month since the fight got signed, 'Colby's in his head, Colby's this, Colby's that'.
"The reason I'm the best in the world is because my mind is stronger than everyone in the division.
"I give him his props, he was tough as nails, he caught me a few times but my mind is stronger than all these guys, I can prevail. I keep marching forward."
A packed card saw Max Holloway lose his featherweight title to Alexander Volkanovski, while Amanda Nunes retained her bantamweight belt with victory over Germaine de Randamie.
UFC legends Jose Aldo and Urijah Faber each lost bantamweight bouts to Marlon Moraes and Peter Yan respectively.