LAS VEGAS - Manny Pacquiao's big win over Miguel Cotto on Saturday was the biggest boxing show of the year, selling 1.25 million pay-per-view buys to best the 1.05 million sold by Floyd Mayweather Jr. for his fight with Juan Manuel Marquez in September.

The television gross was $70 million, meaning both fighters will pocket millions of dollars more than their guaranteed purses.

The strong numbers not only point to a resurgence in interest in boxing in the U.S., but add to the momentum for a possible fight next year between Pacquiao and Mayweather that could be the richest ever in the sport.

"They have to deliver," HBO Sports president Ross Greenburg told The Associated Press. "The American public wants that fight."

Promoters for both fighters have already said they plan to begin negotiations soon for the bout, which would likely take place in early May. Las Vegas casinos have the inside track on landing the megafight, though there has also been talk of holding it at the Dallas Cowboys' new stadium, or even at Yankee Stadium.

One thing is certain: There is too much money at stake for either fighter to not make the fight happen.

"The two best pound-for-pound fighters in the world in the same weight class in the prime of their careers," Greenburg said. "It just doesn't get any better than that."

Promoter Bob Arum agreed.

"The way I look at it now, boxing is really on a roll," Arum said. "We would be idiots now to slow the momentum and the only way we can keep the momentum is to make this fight."

Arum, who represents Pacquiao, is expected to begin talks as early as next week with Richard Schaefer, who heads Golden Boy Promotions and will represent Mayweather in the negotiations. Though each fighter believes he should get a bigger percentage of the purse, the total revenues will be so high that a 50-50 split may not be all that difficult to achieve.

Arum said Pacquiao will end up making some $22 million for his 12th round stoppage of Cotto, while Cotto will end up with around $12 million. That is far higher than either fighter was guaranteed because, as is the case with most big fights, they worked for a percentage of the total sales.

The Pacquiao-Cotto fight also did well at the live box office, with 15,470 tickets sold for a gate of $8.84 million at the MGM Grand hotel.

The potential of a Pacquiao-Mayweather fight is so big that Arum said casino magnate Steve Wynn had already spoken to him about constructing a 30,000-seat outdoor arena on what is now a vacant lot across from his two resorts to host the bout, with other casinos joining in as partners. Outdoor arenas were a staple of the big fights in Las Vegas in the 1980s, beginning with the Muhammad Ali-Larry Holmes fight at Caesars Palace.

"A lot of people are interested," Arum said. "The problem with having it in the East, though, is that the taxes are so big that the fighters would have to give up millions in extra taxes."

Greenburg said the numbers for Pacquiao-Cotto gave HBO its first back-to-back pay-per-view fights that sold more than 1 million homes since 1999, when Lennox Lewis-Evander Holyfield and Oscar De La Hoya-Felix Trinidad did the same thing. The biggest pay-per-view ever was the 2007 fight with De La Hoya and Mayweather that got 2.4 million buys.

Greenburg credited the recent strong sales to a new willingness by promoters to match their best fighters, and to the new _ and younger _ fans drawn to the sport by the success of the network's "24/7" reality shows in the weeks before the fights.

There would be no lack of material for a Pacquiao-Mayweather show, which would match a Filipino hero with a colorful cast surrounding him against a fighter with a dysfunctional family who has played the role of villain in his biggest fights.

"There's just so much drama and subplots for this," Greenburg said.