He said he expected McGregor, who has never fought a professional boxing match, to try to pummel the defensive-minded Mayweather, who is putting his flawless 49-0 record on the line.

There's a reason this fight is a sanctioned boxing match and fought under his skill set.

Well, yes, the interest has been shown, as per UFC President Dana White. He's been a defensive fighter for a decade, and the best at what he does, so if McGregor happened to threaten him he'd naturally revert to his defensive instinct.

McGregor retorted: "You haven't knocked anyone out in about 20 years".

"There's some psychological warfare going on, " McGregor said. From a distance, the attire looked classy, but a closer look revealed the words "F**k You" were used to form the pinstripes.

Starting this week, Mayweather and McGregor are going on a four city tour to promote their fight.

"He can't even afford a suit anymore", said McGregor.

"He's got little legs and little hands. He gets off a flight from Ireland, looks like he was just fitted at Armani, walks off the plan and says, 'I will knock this man out within four rounds, '" White said on Speak For Yourself.

Three names have been confirmed for the undercard of Mayweather v McGregor although none have an opponent yet.

Perhaps the American was contenting himself with the knowledge that if McGregor had arguably won round one of their verbal jousting the 12-time world champion has been installed as the heavy favorite for their August bout.

The Big3 said Tuesday it reached a financial and promotional deal with MGM Resorts, Mayweather Promotions and UFC.

McGregor has never boxed professionally, and unlike MMA rules, he will not be allowed throw kicks, knees and elbows in the fight.

Despite Mayweather's age, he is heavily favored to win. After that, he held up a $100 million check that he hadn't yet cashed. I hope it is a good fight.

On Monday, it was revealed that the pay-per-view event would cost $89.95 for standard definition and $99.95 for high definition.

The media conference was the first in a four-day global tour promoting the bout.