Conor McGregor sent a vicious series of messages to Bellator middleweight champion Gegard Mousasi after he spoke out about his boxing fight with Floyd Mayweather.
The Irish star fought in a crossover bout with retired star Mayweather in 2017 in a fight which is the second-biggest selling in combat sports history with around four million pay-per-views sold.
He was ultimately defeated but generated up to $100million from the clash.
Mousasi has now revealed that McGregor contacted his management after he talked about the boxing fight, to which he responded with an insult of his own.
“I said something about it (the boxing match with Mayweather), and the idiot sent me a private message," Mousasi said during the MMA Hour. "Actually, he sent it to my manager because I don’t do Twitter.
"That was it, and I then said to manager, write something back, he’s a moron. He said, ‘don’t bring my name in your mouth,’ and I said, you’re a ginger-headed f***.”
“In the interview I mentioned, they were talking about respect or whatever, and then he texted me on Twitter. He messaged me, and I said, ‘what’re you going to do with your 50kg?’
"And then he was, I don’t know, he was philosophical or whatever the f*** he was writing, he was like, ‘a knife is lighter than a pound, it can cut from ear-to-ear,’ whatever the f*** he was writing.
"That guy is a bum. He’s a 50kg guy, what the f*** is he going to do? I bet if he’s face-to-face, he’s not going to say that. But you know, Twitter gives some people courage.”
McGregor's fight with Mayweather was billed as the "Money Fight' but the Irishman was unable to prevail against the natural boxer who secured a late stoppage.
He has since gone on to return to the UFC where he had so much success only to be defeated by Khabib Nurmagomedov.
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The 33-year-old has suffered a decline since his fight with Mayweather with just one victory to his name against Donald Cerrone.
Dustin Poirier defeated McGregor twice last year with McGregor suffering a broken leg in their trilogy bout in July.
UFC lightweight Mason Jones believes McGregor should have retired after his defeat to Mayweather in the boxing ring.
"I think [ Conor McGregor ] did well," Jones told SportsKeeda MMA. "I just don't understand why he came back into MMA after the whole Mayweather stuff.
"Like, when you make into that realm, live a lifestyle and enjoy. There are other ways to make money, but he does love MMA, that's easy to see.
"I think he is who he is and I don't think he sort of surrounds himself with the right people. I just don't think the second fight vs. Poirier was a good move."
