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."
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.