When McGregor 'touches people they go to sleep'

Dana White has warned Floyd Mayweather that if Conor McGregor lands one blow in their super fight, it's 'lights out' for the boxing great.

The UFC boss laughed off the widely held assumption that the Irish fighter will be thoroughly outclassed in a 12-round boxing contest.

WAR OF WORDS: The trash talk battle between Conor and Floyd

Speaking on Fox Sports News, White argued that anything is possible once the two fighters step into the ring.

"If you look at Conor's size, youth, knock out ability, it's crazy to think that he couldn't pull this off," White said.

"Even though it's a straight boxing match, Floyd Mayweather is 40 years old and he hasn't fought in over two years.

"If you want to look and see if there's any kind of chink in the armour, it's against southpaws.

"Conor McGregor is 28 years old, he is a southpaw and when he touches people, they go to sleep.

"So the question is in a 12-round fight, can Conor McGregor touch Floyd Mayweather."

Months of negotiating and trolling finally came to an end Wednesday as a blockbuster bout for August 27 (AEST) in Las Vegas was confirmed.

Mayweather, 40, will come out of retirement and put his flawless 49-0 boxing record on the line against UFC champion McGregor in the ring.

McGregor has his doubters as he steps away from what he knows best — the octagon and mixed-martial arts — to go toe-to-toe with Mayweather, but the Irishman is full of confidence.

The opening money line tabbed Mayweather as a huge favorite at -2,250 with McGregor at +950.

While terms of the deal have not been made public, White's UFC brand stands to benefit greatly from the fight. He has said previously Mayweather could pocket around $100 million, with McGregor hauling in around $75 million — a record payday for McGregor. The pay-per-view is expected to gross about $475 million.