He has not fought since with his first child due this summer but appears determined to make a comeback in the boxing ring as opposed to the MMA octagon.
The Irishman has repeatedly talked up a mega-fight with boxer Floyd Mayweather Jr, who is unbeaten in his 49-fight career.
Conor McGregor: 10 things you didn't know about the UFC star
Wed, November 23, 2016
Express Sport reveals some hidden facts about the UFC star
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When McGregor travels for fights, he always needs to carry a passport for his shoes as certain states restrict certain materials. His favourite pair are made from crocodile skin
The 39-year-old officially retired in 2015 but he has admitted that McGregor is the only opponent for whom he would return to the ring.
But Mayweather Jr's father and trainer has no doubt that his son would win the bout, and doesn't think that even he would be able to train McGregor to a level where he could be competitive.
"Brother, that right here is a no-can-do deal," Mayweather Sr told Fight Hub.
Floyd Mayweather Sr believes Conor McGregor's boxing skills are not up to scratch
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Conor McGregor's left hand is feared throughout MMA but now he wants to take on the boxing world
"I can’t make Conor McGregor turn around from being a caveman fighter, I don’t know what he is.
"I’ll let my son fight McGregor and I’ll take on his trainer, whoever he is.
"I’ll knock his trainer out, I don’t even know who he is and I will knock him straight cold."
McGregor's head coach is John Kavanagh, a jiujitsu specialist.
And unlike Mayweather Sr, he is confident that McGregor's preparation for a boxing match would be significantly easier than their normal training camp.
Floyd Mayweather Jr is just as confident as his father about winning
"It would actually almost feel like a break for us because we wouldn't have to keep up the other skill sets," Kavanagh told the Daily Star.
"In mixed martial arts your trying to work on seven or eight different skill sets.
“Whereas in boxing, it's one – it's just boxing."