Conor McGregor's fight on Saturday against Floyd Mayweather is his first ever professional boxing contest
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 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."
Why the Tuesday chaos?
Floyd Mayweather is a former five-weight world champion
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.
McGregor was due on stage first but with both men late for the event, his rival stepped up, leaving the Dublin fighter to follow when he arrived.
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. McGregor exchanged hated words with one member of the Mayweather group and later rowed with ex-sparring partner Paulie Malignaggi.
Conor McGregor is the UFC lightweight champion
"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.
-- Courtesy of BBC Sport