Conor McGregor has received a social media beat-down that rivals his days in the Octagon after posting a derogatory tweet about a rival's Muslim wife.
The comment came after UFC superstar McGregor announced his retirement from mixed martial arts last week.
But Khabib Nurmagomedov, who fought and comfortably beat McGregor in the UFC last year, expressed scepticism at his opponent's decision to leave the sport.
"Conor acts like a jealous wife, who says 'I will leave' all the time but then comes back," the Russian said in response to McGregor's initial tweet.
But McGregor, known for his lethal verbal comebacks as much as his physical fighting abilities, jabbed back, adding fuel to the fire of his feud with Nurmagomedov.
"Your wife is a towel mate," read the tweet, which was accompanied by a picture of Nurmagomedov and his wife, who was wearing a hijab, on their wedding day in 2013.
The tweet was quickly deleted, but by that time social media had already exploded into life, with screenshots of the tweet shared widely.
Immediately, responses began to flood in calling McGregor a racist, and condemning his response.
"I really have to question your motives as a human being," one person wrote.
"Guess @TheNotoriousMMA really is an uneducated racist mut (sic)," said another.
"He clearly has enough money to pay someone to explain to him how an insult may be harmless in one culture and be UNBELIEVABLY offensive in another," a third person added.
McGregor has yet to apologise or acknowledge his now-deleted comments.