LAS VEGAS - The moment of truth for Manny Pacquiao and Floyd Mayweather finally arrived on Saturday in a blinding blaze of star-power at the MGM Grand Garden Arena.
Filipino icon Pacquiao was bouncing and beaming as he made his way from his dressing room to the floor of the arena, cheers of "Manny, Manny" ringing out.
He paused to take a selfie with trainer Freddie Roach then began the walk through the crowd in the darkened arena to a tune of his own composition.
Unbeaten American Mayweather followed, his eyes shielded at times by the bill of his "Mayweather Promotions" cap, his visage serious as he climbed through the ropes.
By the time announcer Jimmy Lennon Jr announced "It's go time" signalling the rivals' imminent arrival, the atmosphere was electric, which seemed ready to burst at the seams from sheer excitement.
Stars spotted as the buzz built was a who's who of sports and entertainment giants: NBA legend Michael Jordan, actor-director Clint Eastwood, music icon Sting.
Tantalizing glimpses of the fighters preparing in their dressing rooms drew cheers when they were displayed on giant video screens.
As the undercard bouts unfolded, ring great Muhammad Ali sent his own good wishes to both fighters via Twitter.
"Rumble young men rumble," Ali tweeted. "Good luck to Manny Pacquiao and Floyd Mayweather." As the main event approached and the stars came out, the electricity grew.
For superstar tennis couple Andre Agassi and Steffi Graf the fight was just a night out on the town, they live in Agassi's hometown of Las Vegas.
But many more had jetted in for the event - evidenced by the pictures tweeted of the crush of private aircraft jamming the Las Vegas airport.
That included a bevy of Hollywood stars that included Denzel Washington, Bradley Cooper and Jon Voight.
Actor Mark Wahlberg was in attendance, no departure for a man who is a regular at the Wild Card gym in Hollywood, run by Pacquiao trainer Freddie Roach.
NFL quarterback Tom Brady, who guided the New England Patriots to a Super Bowl title in February, looked cool as ever as he entered the arena in a slick suit and sunshades.
Earlier Saturday Brady and team-mate Rob Gronkowski were across the country at the Kentucky Derby, the event that usually dominates the US sports landscape on the first Saturday in May.
But even the first jewel in US flat racing's Triple Crown has paled in comparison to the welterweight world title showdown dubbed "The Fight of the Century."