Conor McGregor has been slammed after a Tweet from his account included an alleged 'racist slur' directed at rival Khabib Nurmagomedov's wife.
The tweet posted overnight read: "Your wife's a towel mate" as he laid into the UFC star following a number of arguments between the pair.
Two pictures were then shared of her wearing a traditional Islamic face veil, but later removed after a backlash.
The messages were branded racist and Islamophobic on social media, as Nurmagomedov is a Muslim.
During the late night tirade, McGregor's account also took aim at the Russian's brother, tweeting "I smacked your brother around and took a s*** in this hat".
In tweets which have remained, he had a pop at the 30-year-old for what he says is him avoiding another fight.
"Don't be scared of the rematch you little scurrying rat," he tweeted.
"You will do what you are told like you always do."
There's bad blood between the fighters after Khabib defeated McGregor in Las Vegas last October.
Speaking on Tuesday in his native Moscow, Nurmagomedov said that McGregor “couldn’t reach a deal with the UFC so they feel they’ve lost him and they could lose money”.
“I don’t think he’s finished,” Nurmagomedov said. "Conor acts like a jealous wife who says ‘I will leave’ all the time but then comes back.”
McGregor retired from UFC last week but is already set to hold talks with President Dana White about a U-turn.
The former two-weight champion tweeted that he was calling time on his mixed martial arts career but he could be set to return.
White believes McGregor is simply attempting to negotiate a better deal, as he did when he first retired three years ago
He said: "I think that there’s some things that Conor wants and I think that Conor wants to get together face to face, he and I, and we probably will in the next couple of weeks and we’ll get this thing figured out."
McGregor has long desired part-ownership of the UFC which was sold to Hollywood talent agency WME-IMG for Sh400 billion in 2016.
He has featured in five of the six biggest pay-per-view events in the company's history, pulling in almost eight million buys in the United States.
The UFC also earned a significant sum from McGregor's defeat by Floyd Mayweather which generated Sh60 billion in 2017.