Shane Mosley, here confidently flexing at the weighin before his demolition of Antonio Margarito, has reason to smile. The 37-year-old veteran is now positioned to make a fortune from potential mega-fights with Floyd Mayweather Jr. and the winner of Hatton-Pacquiao. Photo / Tom Hogan-hoganphotos.com

What a difference one fight can make.

After a competitive loss to Miguel Cotto in November of 2007, most observers felt that Shane Mosley’s bold stand against the then-undefeated up-and-comer was the perfect note to end his decorated career on.

Ten months later, Mosley looked all 37 of his years as he struggled to defeat Ricardo Mayorga.

Even after he found his rhythm and his mark (Mayorga’s chin) in the final round of the bout, knocking his stubborn foe cold with a second to spare, the general consensus was that Mosley should hang up his gloves before he gets seriously hurt.

When the prospect of Mosley facing Antonio Margarito was brought up immediately after the Mayorga fight, the ringside media unanimously dismissed the matchup as an ill-conceived one-sided slaughter.

The fight was not ill-conceived, as the 20,820 fans who packed Staples Center Saturday proved, but it was a one-sided slaughter – of Margarito.

Mosley’s breathtaking ninth-round stoppage of one of the sport’s most respected tough guys did more than earn the Southern Californian his fifth major title. It made him the man to beat in the welterweight division.

The potential fights that can be made with Mosley are as numerous as they are intriguing.

There are rematches with Margarito and Cotto. There’s fellow 147-pound title holder Andre Berto, the undefeated young fireplug who recently proved his mettle by gutting out a close 12-rounder against Mosley victim Luis Collazo. There’s the winner of the May 2 junior welterweight showdown between THE RING champ Ricky Hatton and pound-for-pound king Manny Pacquiao.

There are formidable top-five contenders at welterweight and junior middleweight – including Mosley’s old foe Vernon Forrest, triple division threat Paul Williams, and welterweight titlist Joshua Clottey – who would love to take on the Sugar Man.

However, the best opponent for Mosley, according to Richard Schaefer, isn’t ranked in any weight class because he officially retired last summer.

“Floyd Mayweather makes the most sense,” the CEO of Golden Boy Promotions, Mosley’s promoter, said Sunday. “I think Mosley-Mayweather could be one of those all-time great boxing events that captures the imagination of the public.

“It has the potential to be a big-time showdown that attracts a huge star-studded crowd like (Ray) Leonard-(Thomas) Hearns or (Marvin) Hagler-Leonard did decades ago. I really believe it could be one of the biggest fights in recent history because of the way Shane destroyed Antonio Margarito and because of the respect Mayweather has from remaining undefeated for so long and having dominated so many divisions.

“A month ago, (Mayweather representative) Leonard Ellerbe said that Mayweather would return to the sport if the right deal was on the table. I hope the challenge of fighting Mosley is big enough for Floyd to come back.

“Monday, I’m going to call (Mayweather’s advisor) Al Haymon and see if there’s interest in the fight.”

Schaefer has other important business Monday morning, mainly receiving a signed contract from Hatton to consummate the on-and-off-and-on-again Pacquiao fight.

“I’m hoping to get a signature from Hatton so we can finally put this fight to rest and start setting up the media tour,” he said.

The winner of Hatton-Pacquiao is Schaefer’s second choice of opponent for Mosley if Mayweather can not be lured from retirement.

A rematch with Cotto is Schaefer’s third choice.

Other top 147-pound contenders, such as Berto, don’t interest the promoter.

“I don’t think Berto is ready yet,” Schaefer said. “He’s still developing as a fighter and he’s still developing his name. He’s a very good young fighter and I think there are other very good fighters out there like Paul Williams and (Joshua) Clottey, but those fighters would not make for a big event.

“Mayweather, the winner of Hatton-Pacquiao and Cotto are a notch above the rest. They make for interesting fights, they have a name and they have fans.”

Margarito, who was stopped for the first time in his career Saturday, recently emerged as a fighter with a significant fan following. Most of the fans who packed Staples were there to cheer on the titleholder from Tijuana.

However, Schaefer believes the public wouldn’t buy into Mosley-Margarito II.

“It was too one-sided for an immediate rematch,” he said, “and as Bob Arum said, speed always kills power. Margarito can come back and be as successful as he once was, but Mosley would probably beat him 10 times out of 10 because of his hand speed.”

Before Saturday’s fight there was talk of a Margarito-Cotto rematch in June, but there are no immediate plans for the Mexican mauler following his devastating loss to Mosley, according to his promotional company Top Rank.

“It’s too soon to talk about what Margarito will do next,” said Top Rank publicist Lee Samuels. “Our guy took a pretty bad beating Saturday. He went to the hospital with a headache. He had a minor headache before the fight. We’ll wait a week or two before sitting down with Margarito’s team. People deserve time to regroup. Fighters deserve time to recover.

“We’re still interested in making the rematch with Cotto, but we have to keep in mind the punishment Margarito took against Mosley and we have to remember how grueling (Margarito-Cotto) was. We have to see what Cotto looks like in his next fight (against Michael Jennings) Feb. 21. Maybe June is too soon for that fight.”

What a difference one fight can make.

Doug Fischer can be reached at [email protected]