The UFC superstar and the undefeated five-weight world champion meet inside the boxing ring in Las Vegas on 26 August in what is expected to be the richest fight in combat sport history. On Tuesday (11 July), they kicked off the first leg of their four-city promotional world tour at the STAPLES Center in Los Angeles in front of a 22,000 sell-out crowd.
Taking the stage for the first time, Mayweather barely batted an eye lid as McGregor began berating him for showing up in a tracksuit. "He's in a f*****g tracksuit, he can't even afford a suit anymore. The [Rolls] Royces outside are 2012. He's f****d."
Bringing attention to his own outfit, McGregor proclaimed: "If you zoom in on the pinstripe, it says 'f**k you."
He wasn't lying. Picked up by ESPN's Brett Okamoto, McGregor's not-so-subtle message to his opponent was clear to see. The Dubliner even promised to release his own line of custom suits later down the line.
Mayweather gave as good as he got during the heated face-off between the two, however, reminding those watching on of McGregor's submission defeat to Nate Diaz at UFC 196 - his only defeat to date while fighting with the Las Vegas-based promotion.
"We know Mr. Tap-out likes to quit. And you will wave that little white flag," Mayweather said. "Either you going out on your face, or you're going out on your back. I' not the same man I was 10 years ago, I'm not the same man I was five years ago, I am not the same I was two years ago, but I'm better than you."
The circus is now officially in town with further promotional events planned this week in Toronto on Wednesday (12 July), New York on Thursday (13 July) and London on Friday (14 July).