The conference, which was as equally menacing as it was surreal, saw both men introduced to the stage before they each addressed thousands of fans at the Staples Center in Los Angeles.
The pair then faced off, with Dana White and Floyd Snr both on hand to prevent things from overheating when both Mayweather and McGregor began animatedly shouting in each other’s faces.
Both men were then quickly dragged away ahead of Wednesday's encounter.
The press conference was the first in a whistle stop press tour, with similar events being planned on Wednesday, Thursday and Friday, with the last conference due to be held in London.
The fight is scheduled to take place in Las Vegas on August 26, at the T-Mobile Arena.
But what five things did we learn from this dramatic first press conference?
McGregor has the public on his side
Hardly surprising — but this first press conference made it absolutely clear that Conor McGregor has the public on his side.
A large number of the fans assembled for the LA press conference arrived either decked out in UFC merch or proudly waving Irish flags, and Mayweather even had a flag lobbed at him as he made his way to the stage, surrounded by heavies.
Showtime chief Stephen Espinoza was roundly booed as soon as he began wittering on about Mayweather’s legacy, while UFC president Dana White was cheered loudly when he introduced McGregor.
And then there was the reaction to the two men themselves. Mayweather was repeatedly drowned out with jeers, while McGregor only had to raise his hand to the air to be greeted with the sound of thousands singing his name.
Mayweather attempted to sabotage his rival
The most revealing line of this press conference? It wasn’t anything said by either one of the suits — Espinoza or Richard Sturm — and it certainly wasn’t anything said by White, who treated the LA crowd to all of about 12 words.
Nope. Predictably, it was something said by McGregor.
“They tried to catch me by surprise, I didn't even know I was meant to be giving a speech,” he admitted after being presented a mic and told to address thousands of screaming fans. “F*** it. I’m enjoying myself up here.”
Factor in the way in which McGregor was quickly lead to the stage, and the face that his walkout music kept cutting out, and you can be certain of the fact that Mayweather deliberately did his best to sabotage McGregor’s evening. And yet still the Irishman kept smiling…
Conor clearly wasn’t meant to have a mic…
After McGregor had finished with his impromptu speech, Mayweather took to the mic.
The undefeated boxer launched into a clearly pre-organised speech, with members of his entourage chanting his slogan back at him, rapgod style. But he hadn’t reckoned on something: nobody had taken McGregor’s microphone away from him.
Cue an avalanche of hilarious interjections. When Mayweather promised to knock McGregor out, the Irishman gleefully interrupted that he hadn’t managed that in 20 years. And when Mayweather produced a $100m cheque for the benefit of the crowd, McGregor yelled: “That's for the taxman!”
It didn’t take long for those in charge to cut the mic, much to McGregor’s annoyance.
This fight is going to be political
After the fight, the massive PR operations around both men quickly sprung into action.
Some chalked it up as a flawless victory for Mayweather. Others said that McGregor wiped the floor with his rival. Either way: it was difficult to get a straight answer on who got the better of the first press conference.
That’s unsurprising. Mayweather and McGregor are two of the most powerful men in sport and neither can afford to lose face at this early stage. The build-up to this superfight is therefore going to be very, very political.
And this is actually going to happen…
Finally, just seeing the two men stood side by side hammered home that this fight is actually going to happen.
It’s ridiculous. The greatest defensive boxer in the history of the sport — if not the greatest boxer in the history of the sport period — taking on a man who hasn’t boxed competitively since he was a teenager, with a pro record of 0-0.
But money talks, and the two men are actually going to get it on. There is absolutely no chance McGregor will beat Mayweather in the ring. And yet that small fact isn’t likely to stop anyone from watching.
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