Conor McGregor on Floyd Mayweather: "I'm going to break his face"

Conor McGregor, the reigning UFC Lightweight Champion, has once again thrown down the gauntlet to retired boxing legend Floyd Mayweather, who, too, has taken several pot shots at the Irish fighter in recent weeks.

The potential McGregor vs Mayweather dream match-up began to pick up steam after the mixed martial arts fighter obtained a boxing license from the state of California earlier this month.

Last week, Mayweather, who retired from the boxing ring with a 49-0 record, taunted McGregor on Instagram by posting a video of the Irishman losing to Nate Diaz at UFC 196. The American asked his followers to fill in an appropriate caption, promising to give out $US10,000 ($AU13,946) to the poster with the best caption.

Conor McGregor vs Floyd Mayweather: The dream fight

Mayweather, who hasn't returned to the ring since his fight with Manny Pacquiao last year, followed up his Instagram post by claiming that, "I’m f***ing McGregor up. Punk-a** McGregor. I’m gonna (going to) slap McGregor. I’m gonna (going to) slap the s**t out of McGregor when I see him.”

Last week, UFC president Dana White was adamant that the younger and hungrier McGregor would be too much to handle for the 39-year-old Mayweather. "There's a lot of talk going on between Floyd and Conor right now. If they were to box, look at Manny Pacquiao vs Floyd Mayweather. It was a fight that everyone wanted to see for years. It took almost 10 years to make that fight and they are the same sport. There's no way this fight would ever happen," White told a morning show on Fox Sports, via Yahoo Sports.

White went as far to say that the fight could put Mayweather on shelf. "If they really fought it would be ugly. It would be ugly for Floyd. Conor has more weapons and tools than Floyd Mayweather does."

McGregor, 28, recently announced that he was taking time off until at least May for the birth of his first child. But that hasn't stopped the 'Notorious One' from taking barbs at McGregor. On Christmas Eve, McGregor tweeted the following to remind the world that his potential bout with Mayweather could happen next year.

If Conor McGregor vs Floyd Mayweather takes place, it will likely go down as the most lucrative fight in combat sports history. Recently, one business analyst suggested that Mayweather could purse over $US500 million (AU$697 million) from the fight. Will fantasy warfare turn real? Time will tell.