Both men faced off at a press conference in Los Angeles yesterday, the first in a series of publicity events this week ahead of the main event on August 26th.
Speaking in Los Angeles at the first stop of a four-city media tour which will also take in Toronto, New York and London over the coming days, McGregor said on a Showtime live stream: "I am honoured to be here, to give you this spectacle".
"Believe half of what you see and none of what you hear, especially when it comes to media in this country", Mayweather wrote.
Mayweather, who has already made an estimated $700 million during his two-decade career, is set for another eye-watering payday against brash UFC star McGregor.
"He's in a (expletive) track suit", McGregor shouted out.
"Let me show you [expletives] what a $100 million fighter looks like".
Mayweather, who retired as an undefeated professional world champion, is considered one of the greatest boxers in history.
On Monday, it was revealed that the pay-per-view event would cost $89.95 for standard definition and $99.95 for high definition.
Speaking afterwards, McGregor claimed his mic had been turned off.
After the joint press conference, Irish UFC icon McGregor held a briefing of his own. Though Mayweather has a flawless 49-0 record and is looking to better it, McGregor is no spring chicken.
On Aug 26, this man will be unconscious, he's too small, he's too frail. But I think it's definitely been contracted that McGregor can't touch Floyd in any way, shape or form, it's off. "How's this suit look?" "But I got enough to beat you". At the end of the day, McGregor's only 28, and he has talked about adding to his legacy, and pursuing other titles in the past year.
"They fought way before me and haven't fought since". McGregor still has a chance get his chops in and emerge the victor as the tour continues Thursday in Toronto, Friday in Brooklyn and then the final stop on Saturday in London (all AEST). After all, it's really hard to top the "f**k you" suit he just wore.
Second seed Halep ends Azarenka Wimbledon bid
Usually that's a good principle to follow, but when it's windy let the ball bounce and then hit your overhead. I'm definitely digesting things a bit still. "I don't think there's anything different that's happening".
Nadal out! Rafa's Wimbledon 2017 is over in shock defeat
Venus Williams, whose lukewarm Wimbledons earlier this decade suggested a fade, persisted with obliterating that notion on Monday. Nadal had made serene progress through the draw until he faced Muller who stunned him by taking the first two sets in 74 minutes.