LAS VEGAS — They met a year ago this week in a fight that was the richest ever, even if it disappointed most of the millions who watched it.

Now there are rumblings, however slight, that Floyd Mayweather Jr. and Manny Pacquiao might be persuaded to do it again.

“I would say there is a possibility a rematch happens, yes,” promoter Bob Arum said Monday. “How big a possibility that is, I can’t really measure.”

Mayweather helped stir speculation over the weekend by saying in a Showtime interview that he might be persuaded to come out of retirement if the money was big enough. He said he had talked to Showtime and CBS about another fight and that “some crazy numbers have been thrown my way.”

Though Mayweather wasn’t asked specifically about Pacquiao, the Filipino might be the only opponent who can help him reach those numbers.

“If I came back, of course, it would have to be a nine-figure payday and probably a championship fight and a nine-figure payday,” Mayweather said.

Showtime executive vice president Stephen Espinoza said he is among the minority in boxing who believe Mayweather won’t come back. But Espinoza said he also believes a second fight between Mayweather and Pacquiao would do well.

“All of us here would love to see that fight again, or any other fight with Mayweather,” Espinoza said.

There wouldn’t seem to be a great appetite among boxing fans for a rematch of the bout that sold 4.6 million pay-per-views, but got lousy reviews. Mayweather won the fight by unanimous decision, and afterward Pacquiao revealed he fought with a shoulder injury.

Both fighters are also technically retired, and Pacquiao is in the middle of a campaign for Senate in the Philippines that, if he wins, would make it difficult for him to fight again.

But Pacquiao could be tempted by a chance to avenge his defeat. And Mayweather could be lured back into the ring not only by a big payday but a chance to break Rocky Marciano’s 49-0 record and win fight No. 50 in his pro career.

“Obviously he’s coming back,” Arum said of Mayweather. “And I can’t see him making the kind of money he’s talking about with anybody other than Manny.”

Both fighters have fought once since the big fight, with Mayweather beating Andre Berto last September and Pacquiao defeating Timothy Bradley last month. Both fights were pay-per-view busts, with sales in the range of 400,000, a tenth of what they sold in the ring together.

Arum said the tepid box office performances were largely a result of a hangover from last May’s fight. Many fans who spent a record $99.95 to buy the fight at home felt they got taken by a lackluster bout that didn’t come anywhere near living up to its hype.

Arum said it will be hard for either fighter to move forward without the other.

“If they fight anybody else there’s going to be that hangover,” he said. “If they fight each other, people will be attracted to the fight. It won’t do what the last fight did, but it might do 50 percent of the last fight.”

That would be enough to make Mayweather his nine-figure purse. It would also be enough to give Pacquiao a huge payday, if not the $100 million or so he took from the Mayweather fight.

And, as proven in the first fight between the two men that grossed some $600 million, anything can happen in boxing if the money is right.