The opening event of a week of build-up to potentially the most lucrative fight in boxing history produced chaotic scenes in Las Vegas, with Floyd Mayweather booed by unhappy fans.
The undefeated American arrived late and was barely visible, entering amid a large entourage before being largely hidden on stage by a media scrum.
Conor McGregor, his UFC champion challenger, then arrived and made a beeline for an Irish flag in the crowd before performing an impromptu lap of fans, as media and security gave chase.
Once on stage, the 29-year-old Irishman said he would be “calm and cold” when he met the former five-weight boxing world champion on Saturday.
“He needs to be put to sleep,” said McGregor. “He will wake up a better man. I am going to do that for him.”
‘McGregor can win big whatever happens on Saturday’
BBC 5 live sports correspondent Richard Conway
This was hype and showmanship taken to a whole new level.
When Conor McGregor finally walked on, he did so as the self-styled people’s champion, strutting around the open plaza as if he owned it.
Like a presidential candidate on the eve of polling day, he shook hands and high-fived as many supporters as he could reach.
Dressed in a purple suit, he told his expectant audience he would knock Mayweather unconscious on Saturday night, which elicited a huge cheer.
As he tried to depart I managed to ask him if he really is, as he claims, going to shock the world on Saturday night.
Nodding, he turned to the crowd and said “for these fans, I love these fans”.
McGregor’s legend continues to grow. It increasingly feels like he stands to win big in the long term, no matter what happens in the ring this weekend.
Why the Tuesday chaos?
About 1,000 media from around the world have been accredited for Saturday’s bout, many of them to be housed away from the venue at a media tent a short walk from the T-Mobile Arena.
Outside the arena, a large security presence tried to keep the ‘Grand Arrivals’ ceremony cordial on Tuesday afternoon.
Undercard fighters, including Wales’ Nathan Cleverly, posed for head-to-head pictures without problems, until Mayweather entered, rather later than billed.
He thanked the fans for making the fight happen and stressed McGregor’s boxing debut would not last the scheduled 12 rounds.
But those who had waited in temperatures of over 40C on a street adjacent to Las Vegas’ famous strip showed their frustration when photographers and reporters surrounded 40-year-old Mayweather, blocking any sight of the former five-division world champion.
Cries of “we want Conor” broke out from American fans, while added security was placed at the front of the stage, with media warned not to rush forward when McGregor arrived.
When he did, flanked by his own entourage, they brushed shoulders with the departing Mayweather group, prompting brief panic among the security detail.
“Over the course of the next week, Vegas is Ireland,” said McGregor, after eventually making it to the stage. “We run Las Vegas. We are here to take over this whole city.”
Organisers say the bout – which will be broadcast on BBC Radio 5 live – is the most accessible in boxing history, with fans able to watch through social platforms. They estimate around a billion people will watch worldwide.
It is expected the bout could generate over $ 600m and go close to becoming the richest in boxing history.
Victory for Mayweather, who has come out of retirement for the fight, would take his record to 50 wins from 50 bouts and surpass the late Rocky Marciano’s flawless 49-fight record.