What would appear to be a natural -- a Manny Pacquiao-Floyd Mayweather Jr. super fight -- might not be. Egos, greed and grudges could get in the way.

“It’s a simple negotiation,” Ross Greenburg, HBO Sports president, said minutes after Pacquiao knocked down welterweight world champion Miguel Cotto twice en route to a 12th-round technical knockout Saturday.

“There’s so much money to be made. If it doesn’t happen, there’ll be a revolt. Nothing else is acceptable, and I’m speaking on behalf of the American public and the sport itself.”

But obstacles exist. Will the rich rivals fight over who gets more than a 50% cut of the purse? Of course. Can Mayweather and Bob Arum, Pacquiao’s promoter, set aside their deep personal dislike? Perhaps.

Richard Schaefer, the Golden Boy Promotions chief executive who has promoted Mayweather’s last three fights, expressed confidence that he’d be able to work with Arum to make a Mayweather-Pacquiao fight.

Schaefer told The Times he planned to speak today with Mayweather and Arum. Pacquiao said, “It’s my job to fight. It’s my promoter’s job to pick the fight.”

Said Schaefer: “Bob and me -- how often have we failed to make a big fight?”

Yet, that deal is expected to require a diplomatic effort on a scale usually reserved for the State Department.

Mayweather (40-0, 25 knockouts) formerly fought for Arum’s promotional company Top Rank after being an Olympian but left, saying he felt obscured by the popularity of former stablemate Oscar De La Hoya. The mega paydays that followed, against De La Hoya, Ricky Hatton and Juan Manuel Marquez, have emboldened the unbeaten star’s public statements that Arum shorts his fighters, including Pacquiao (50-3-2, 38 KOs).

Arum bluntly said this week that a deal will not hinge on whether he likes Mayweather -- “and I don’t,” he said.

Pacquiao, usually polite, this month directed some verbal blows at Mayweather, saying he doesn’t think the fight will happen because of Mayweather’s attitude.

“I’m sure he doesn’t want to fight me,” Pacquiao said. “With Floyd, boxing is like a business. He doesn’t care about the people around him watching. He doesn’t care if the fight is boring. As long as the fight is over and he gets the money, it’s good. I want the people to be happy. If I was in the audience, I’m going to watch the boxing because it’s a good fight.”

Mayweather hasn’t launched back, but he does strongly believe he’s the world’s best fighter and has made it pretty clear he deserves the larger purse. He was considered the world’s top pound-for-pound fighter before retiring for more than a year and watching Pacquiao seize the title with the battering of De La Hoya, Hatton and Cotto.

Cotto went to the hospital after suffering facial cuts in the loss but said he planned to fight again, with possible foes being Shane Mosley or Antonio Margarito.

As for Pacquiao-Mayweather. . . .

“All we can do is try to encourage both sides to sit at a table and hammer out a deal,” said Greenburg, who likened the situation to the 1971 deal between Muhammad Ali and Joe Frazier, when Ali returned from boxing exile to face the champion Frazier. They settled on a 50-50 purse split of $5 million, Greenburg said.

Why not 50-50 again, with so much cash available?

Mayweather and Pacquiao have displayed tremendous greed. Pacquiao kept asking for more money to fight Hatton in May until the Hatton camp nearly walked.

Now, Pacquiao probably will be able to say his fight with Cotto easily surpassed Mayweather’s million-seller against Juan Manuel Marquez in September. But Schaefer already has a reply.

“How did Pacquiao-Marquez do versus Mayweather-Marquez? How did Pacquiao-Oscar do versus Floyd-Oscar?” Schaefer said, well aware of the disparity.

Greenburg made it clear: “Floyd’s calling the shots for this fight to happen.”

And Arum’s matchmaker at Top Rank, Bruce Trampler, said it’s naive to believe intangibles like “the good of boxing” will influence the deal.

“This has nothing to do with that,” Trampler said. “These are two businessmen who are going to do what’s best for themselves.”

Said Schaefer: “Getting them together is a mega-fight that has to be made. We’d all have to be morons to not let this happen.”

lance.pugmire@latimes.com