It was the night Bono and U2 went to the ringside in Las Vegas "feeling like U2, Dublin, Ireland, and left feeling like the number one group on the planet".
The SuperFight between Marvelous Marvin Hagler and Sugar Ray Leonard - the subject of a new book by Irish author Brian Doogan - was a $100million showdown at Caesars Palace in April 1987 which coincided with U2's shoot for the iconic video to I Still Haven't Found What I'm Looking For, the second track on The Joshua Tree album.
"It was the perfect location for the video," said The Edge. "To see all the gambling, all the strangeness of the American people coming with their savings for the year to Las Vegas to lose it all - we found that fascinating and that's why we went there."
The hottest ticket in town was for ring legends Hagler and Leonard and their contest for the middleweight championship of the world.
Big boxing fans, Bono and the band and a couple of lucky members of the film crew secured their prized seats in the temporary arena on the tennis courts at Caesars in the heart of Vegas's world-famous Strip.
Frank Sinatra led the glittering array of Hollywood stars at ringside, including Gene Hackman, Tom Selleck, Joan Collins, Whoopi Goldberg, Bo Derek, Chevy Chase, Jack Klugman, Billy Crystal and 'Kojak' Telly Savalas.
But it was Sinatra whom Bono was desperate to meet and he made it happen during the build-up to the main event.
"I don't usually hang with men who wear earrings," Ol' Blue Eyes told him with a smile.
Sinatra invited Bono, The Edge, Larry and Adam to see him perform at The Golden Nugget directly after the fight.
"Even for U2, being introduced at ringside shortly before the opening bell to Sinatra and the experience of the fight and melodrama that surrounds any great boxing occasion in Vegas was unforgettable," Doogan related.
"The SuperFight has become part of boxing lore, with Sugar Ray accomplishing one of the greatest feats in the history of the sport to come back from a virtual five-year lay-off to defeat the master of the middleweights, Marvelous Marvin Hagler.
"Being ringside for a fight of such magnitude is an incredible thrill for anyone. Norman Mailer, the great American writer, said it becomes almost physically unendurable to wait for that bell to ring for the first round.
Yet for U2, even at the end of 12 astonishing rounds, the night was only just beginning."
Right across the street from Caesars the man who had done so much to secure Vegas its reputation as the entertainment capital of the world - along with his Rat Pack buddies, Dean Martin, Sammy Davis Jr, Peter Lawford and Joey Bishop - arrived from his ringside seat to perform in front of a sold-out crowd inside the Golden Nugget.
Sinatra was 71 years old but he was still indisputably the Chairman of the Board, the King of Swing, and he made a fuss of his new friends from Dublin whom he introduced from the stage to his star-studded audience, which included fellow Hollywood legend Gregory Peck.
"I want to introduce you to my friends, U2," Sinatra announced.
"These guys are the biggest rock group in the world. They've got millions of dollars. But they sure don't spend their money on their wardrobe."
After the show Sinatra met with U2 in his dressing room and a special bond was forged.
"Can you imagine coming into Las Vegas, 'Never Never Land', and actually going to a Frank Sinatra show in the Golden Nugget at one in the morning after going to the Hagler-Leonard fight?" said The Edge.
"It was hysterical, I mean Gregory Peck was there and all manner of folks. It was amazing and Sinatra was fantastic. What a vibe."
Bono summed up the experience: "We went to Vegas feeling like U2, Dublin, Ireland, and left feeling like the number one group on the planet."
Sinatra had long been one of his idols and Bono ended up collaborating with him on an album of duets, recording their version of, 'I've Got You Under My Skin'.
He was even a guest at Sinatra's home in Palm Springs.
"We spent some time in his house in Palm Springs, which was a thrill looking out onto the desert and hills," Bono said.
"He showed me a painting, one from his own hand. A mad yellow canvas of violent, concentric circles gyrating across a desert plain.
"In my house in Dublin, right by the hole-in-the-wall cellar, I can still look up to see it. 'The painting is called Jazz and you can have it,' he said. Very special."
Bono might have enjoyed another very special night of boxing in Las Vegas several years later even more than he did when he attended the world heavyweight title fight between Evander Holyfield and Riddick Bowe.
Generously, he gave up his ringside seat to Peter Buck of R.E.M., who had never been to a boxing match in his life, while Bono took up a seat further back.
"I don't want to be in front," Bono said.
The man who sat down beside Buck was especially informative and explained the strategy of the fight as it evolved.
It was one of the great heavyweight brawls, made even greater for Buck by the knowledge imparted by his companion for the evening's entertainment, which he enthusiastically relayed to Bono.
"The seat was incredible, the fight was incredible and the guy sat next to me was incredible - he talked me through the fights the whole night," said Buck.
"Who was he?" Bono asked.
"Sugar Ray Leonard," Buck told him.
Bono was crushed. He and Sugar Ray would have had much to discuss.
The SuperFight: Marvelous Marvin Hagler - Sugar Ray Leonard is available via Amazon and all leading bookshops.