Pound-for-pound king Manny Pacquiao, unable to get even a response from Floyd Mayweather Jr. gauging his interest in a fight, instead will defend his welterweight belt against former champion Shane Mosley on May 7 in a pay-per-view fight at the MGM Grand in Las Vegas.

"We came to a meeting of the minds," Top Rank promoter Bob Arum told ESPN.com on Tuesday night after a final meeting with Mosley and his adviser, James Prince, at the Top Rank offices in Las Vegas. "[Top Rank matchmaker] Bruce Trample says it's a very difficult fight. I believe it will be an exciting fight. Shane knows how to fight and how to deal with the speed. Manny is in for a hellacious fight. I really believe styles make fights."

Arum said the fight will take place at the welterweight limit of 147 pounds.

"I know that they think I'm an old man and that Manny is going to beat me. Let them think that," said Mosley, a former lightweight, welterweight and junior middleweight champion. "I still have power and speed. They thought I was done before I knocked out [Antonio] Margarito, too. So they can think whatever they want. I know what I can do."

The deal is not unexpected. For weeks, Arum has been laying the groundwork for the match, an unpopular one with hard-core fight fans because many consider the 39-year-old Mosley (46-6-1, 39 KOs) to be past his prime after going 0-1-1 in his last two bouts.

He was routed by Mayweather in May and fought to a desultory draw with Sergio Mora in a junior middleweight fight in September.

"I hurt Floyd in our fight, but he's a great fighter and has great defense," Mosley said. "What can I do about Mora? Do you really think that was a draw? Come on. I won that fight. He ran from me all night. But Pacquiao? Come on, man. I'm a bigger guy than him and he gets hit. And you saw how I hurt Floyd. Manny is going to come forward and I will hit him on the chin at some point. His defense is not like Floyd's. Manny will come at me, and I will knock him out."

Mosley got the fight with Pacquiao over lightweight champion Juan Manuel Marquez and welterweight titlist Andre Berto. Arum had solicited term sheets from all three before going to the Philippines last week to attend Pacquiao's 32nd birthday party and to go over the particulars for all three potential opponents.

Arum said Pacquiao (52-3-23, 38 KOs) settled on Mosley during a meeting last week and that he wrapped things up with Mosley on Tuesday.

Sugar Shane Mosley will face Manny Pacquiao in a welterweight title bout May 7 at the MGM Grand in Las Vegas. Mark Ralston/AFP/Getty Images

"I thought Mosley was the best draw of the three and it would do the best business," Arum said.

Although Arum was critical of Mosley after his performance against Mora, he was with Golden Boy Promotions -- Top Rank's bitter promotional rival -- at the time. Once he left Golden Boy to negotiate the Pacquiao fight on his own, Arum, who has known Mosley for years and promoted some of his fights, changed his tune.

"They had to be insane, putting Shane in the ring with Mora," Arum said of Golden Boy's decision to match Mosley with a fighter with a tough style who usually makes fights with little entertainment value. "With Floyd, Shane had him in real bad trouble in the second round, so he's capable of doing a really good fight with Manny and Manny knows that. He's talking to [trainer] Freddie [Roach] about doing five weeks of training in the United States rather than four weeks here and four weeks in the Philippines."

Roach said he preferred for Pacquiao to fight Marquez or Berto before Mosley, but said of the match when told it had been agreed to, "I think it's a good fight. I feel that Shane is one of the toughest guys left out there right now. He didn't get up for 'The Contender' guy [Mora], but he will get up for Manny Pacquiao. It's a difficult fight because Shane has speed and power.

"He's getting a little older, which is in our favor, but I expect Shane to be at his best because he's wanted this fight for a long time. I will get Pacquiao well prepared for this one."

Arum and Prince said they were able to make a deal fairly easily because they like each other and, as Prince said, "We're both straight shooters. We cut out all the BS and get straight to the point. I'm excited about the fight. I plan on having a lot of fun. I think it's a great matchup. I think Shane has the speed and power to deliver and I believe we're about to pull off the biggest upset in the history of boxing."

Manny Pacquiao will defend his welterweight belt against Shane Mosley May 7 at the MGM Grand in Las Vegas. Nick Laham/Getty Images

Berto was the long shot of the three because, despite his youth, power and speed, he is not well known and has yet to face a top opponent.

Marquez, however, gave Pacquiao two exciting and bruising fights, both of which ended in controversial decisions.

They fought to a draw in a 2004 featherweight championship fight and Pacquiao won a split decision in a 2008 junior lightweight title fight. Pacquiao against Marquez for a third time also seemed to make sense because Pacquiao's fight date -- May 7 -- falls on the weekend of the Mexican holiday Cinco de Mayo, which is a traditional weekend for a major fight involving a Mexican star.

Arum said the promotion would kick off in early February with a four-city media tour beginning in Los Angeles, followed by stops in New York, Washington and San Francisco, which is home to a sizable Filipino population.

Mosley told ESPN.com that his guarantee for the fight is $5 million with the potential to make millions more from his take of the pay-per-view profits. He and Arum also said Top Rank has a promotional option on Mosley's next fight, win or lose against Pacquiao.

It seems as though Mosley's days with Golden Boy are over.

Under the terms of his deal with Golden Boy he will have to sell back his 4 percent stake in the company for $1,000, although they could wind up in court. Mosley was upset that Golden Boy was pushing Marquez, another Golden Boy fighter, to get the fight instead of him, so he went out on his own to secure the fight.