Conor McGregor has responded to Mike Tyson's claim that Floyd Mayweather will 'kill him' in their upcoming mega-fight and warned his critics they will soon 'eat their words' for doubting him.

The UFC star will make his professional boxing debut against the former five-weight world champion in Las Vegas on August 26.

He is the heavy underdog, given Mayweather is unbeaten in 49 professional fights, and former heavyweight king Tyson recently claimed: "McGregor is going to get killed in boxing... (he) put his dumb ass in a position where he's gonna get knocked out."

But the Irishman, who is expected to pocket a purse of $80 to 100 million for his first boxing fight, responded to Tyson's comments by comparing himself to 'Iron' Mike's former promoter, the legendary Don King.

"That's nice Mike, but you're looking at the new Don King here, son. Money is mine," he said.

The MMA superstar is currently midway through a gruelling training camp ahead of the Las Vegas showdown. He has been sparring with the likes of Paulie Malignaggi, the former two-weight world champion who criticised him for 'disrespecting boxing'.

And McGregor has reiterated his warning that he will prove wrong those who doubt his ability to upset the odds against Mayweather.

The build-up to the August bout has been marred by accusations of racism and homophobia

"You are all going to eat your words for the rest of your days, while I eat lobster for the rest of mine," he wrote on Instagram.

Despite McGregor's inexperience inside the ropes, the August 26 clash is expected to be one of the richest in combat sports history.

The build-up was ramped up by a four-day, four-city publicity tour earlier this month, which was marred by accusations of racism and homophobia.

And McGregor further goaded his opponent by wearing the jersey of NBA star CJ Watson.

Mayweather served 90 days in jail in 2012 for assaulting his former partner and mother of his three children Josie Harris.

It was messages from former Golden State Warriors player Watson to Harris that allegedly prompted Mayweather to attack her in 2010.