A half-hour after
Arum, who has staged some of the biggest bouts in boxing history, said it was difficult to compare fights and fighters across the years but he left no doubt where this one ranks in the contemporary era.
"It's the biggest fight of this century," said Arum, who spoke for about 50 minutes.
Of course the century is only 15 years old. But just in case anyone missed the point, Arum doubled down by calling the Las Vegas bout the "biggest event in the history of the city."
Really? Bigger than Elvis? The Rat Pack?
Pacquiao's trainer Freddie Roach joined Arum a few minutes later and echoed him in saying their boxer would win. Both men were then joined by Pacquaio who, dressed smartly in a dark suit, bright white shirt and red tie, took the seat between them.
Pacquiao's accompanying posse was far smaller than the one that accompanied the unbeaten Mayweather into the room.
Pacquiao's camp made several concessions to get the fight done, reportedly agreeing to a smaller split, allowing Mayweather's name to appear first in any pre-fight publicity and, apparently, allowing Mayweather to go first in Wednesday's press conference.
But Pacquiao said he's OK allowing the favored Mayweather (47-0, 26 knockouts) to take the spotlight
"I like being the underdog," said Pacquiao (57-5-2, 38 KOs). "I think it's going to make me more motivated."
Arum said arranging the Mayweather-Pacquiao fight was the most difficult task he's faced in boxing and credited CBS chief Les Moonves with playing an important role in bringing both sides together and forging a working relationship between the competing camps.
"It took five years," said Arum, who once promoted Mayweather. "A lot of posturing back and forth. I don't want to make any accusations but I guess there was blame on both sides."
Pacquiao, who frequently expressed frustration at the delays, accusing Mayweather of ducking him, said Wednesday the wait has helped make the bout even bigger.
"I believe so," he said. "More people know [about] the fight. Even people who aren't fans of boxing, they know about the fight."
Arum refused to delve into the pay-per-view details other than to repeat widely circulated estimates that the cost will be about $100. Asked for the number of anticipated subscriptions and the take for each fighter, however, Arum demurred.
"You can't satisfy the press," snapped Arum, who said his predictions are frequently twisted. "I'm not saying [anything]. Because I don't know. I really don't know."
But Pacquiao knows one place where sales will be brisk: Back in his native Philippines.