When the fighters were first introduced, they walked out, and appeared to be facing off for a photo-op.

But they kept on walking toward each other, and, were virtually nose to nose before things became testy.

“I didn’t see exactly how it went down,” said publicist, Kelly Swanson, “but apparently, I guess that it was a case of being too close for comfort.”

Next thing everyone knew, Floyd Mayweather and Shane Mosley were grabbing each other by the wrists and shoulders of their snazzy suits, engaged in an on-stage, on-camera scuffle in full view of the media gathered at the Nokia Theatre in New York’s Times Square for Tuesday’s press conference promoting their May 1 clash.

“You’ve got to remember, Floyd and Shane have known each other for a long time. And when they went to face off, there was a little physical contact,” said Swanson, whose Swanson Communications is among the event’s organizers along with Golden Boy Promotions and Mayweather Promotions.

“I guess it was a case of them getting too close to each other,” said Swanson of the skirmish, which was broken up quickly, the third man there being Golden Boy Promotions CEO, Richard Schaefer. “Then, one thing lead to another … Thank God that it didn’t go where it could have gone.”

Their mini-skirmish coincided with the first day of tickets sales for a bout slated for the MGM Grand in Las Vegas, where the 32-year-old Mayweather (40-0, 25 knockouts) and the 38-year-old WBA welterweight (147 pounds) super world champion, Mosley (46-5, 39 KOs) will finally meet after years of eying each other.

Tuesday’s conference was the first of a three-day series of promotional stops scheduled for big cities, with Wednesday’s taking place at the Lincoln Theatre in Washington, D.C., and Thursday’s at the Nokia Plaza at LA Live in Los Angeles.

“It takes two to make a mega-fight. Shane Mosley is one of the best welterweights of our era, and I want to fight the best and continue to fight the best,” said Mayweather, whose victories over Oscar De La Hoya and Juan Manuel Marquez were among the largest-grossing pay-per-view events in boxing.

“I am not only in the fight business; I am in the check-cashing business. I am able to generate millions of dollars,” said Mayweather, who ended a nearly two-year layoff with September’s lopsided win over Marquez. “They say Shane is the WBA champion, but we all know that belts do nothing but collect dust.”

By the time the fighters face each other, Mosley will have been out of the ring for 16 months. The titlist is coming off of a January 2009 ninth-round knockout of Antonio Margarito, who was stopped for the first time in his career.

“It has been a long time since I have had a chance to show the world that I am the best fighter. I have wanted to be the best and have people understand that I am the best,” said Mosley. “May 1 symbolizes something. After this fight, it is going to be clear. It is going to be the date of Mayweather’s first loss.”

The fighters’ contracts include an immediate rematch for Mayweather in the event that he loses, as well as a guarantee that each of the fighters be subjected to Olympic-style, random blood-testing and urinalysis.

Negotiations for a bout between Mayweather and seven-division champion Manny Pacquiao (50-3-2, 38 KOs) fell apart over the notion of random blood-testing, which was being insisted upon by Mayweather.

“When it comes to performance-enhancing drugs, I stepped up to the plate,” said Mayweather. “I want to show the world that my sport is clean.”

The Mayweather and Pacquiao camps’ inability to reach an agreement led to Pacquiao choosing to defend his WBO welterweight title against Joshua Clottey (35-3, 20 KOs) of Ghana on March 13 at Cowboys Stadium in Arlington, Texas.

Mosley had been scheduled to face 26-year-old, WBC champ Andre Berto (25-0, 19 KOs) on Jan. 30, before a distraught Berto pulled out of the fight as a result of the death of eight relatives during the recent earthquake in Haiti.

Mosley has agreed to the Olympic-style drug testing, even as he once admitted to using the steroids “the cream” and “the clear.”

“I just want to say I am going to take my hat off to Mayweather. For a minute, I wasn’t going to get a fight from any of these top fighters, and now I will,” said Mosley.

“I would like to say that it is going down May 1, and it is going to be me and Money Mayweather,” said Mosley. “After this fight, there won’t be anything else to pick. It is going to be clear that there is an a** whooping, and I am about to give it to him.”

In the aftermath of Mayweather’s rout of Marquez, Mosley jumped into the ring, interrupted Mayweather’s post-fight interview with Max Kellerman and challenged him.

But Mayweather’s adviser, Leonard Ellerbe, has said that Mayweather initially began calling out Mosley 10 years ago in 1999, when the Pomona, California resident still was a 35-pound champion and Mayweather a 130-pound titlist.

“This fight has been in the making for 10 years. It’s going to be a hot, hot fight. Shane knows what’s coming. He just doesn’t want to admit it, but he knows. Floyd ‘Money’ Mayweather is ready,” said Ellerbe. “There is a difference when you are talking about Floyd. Once you get your a** up in there, it is a whole different ball game.”

Mosley defended his IBF lightweight title for the last time in April of 1999 with an eighth-round knockout of John Brown.

Mosley then skipped over the junior welterweight (140 pounds) division, immediately entering the welterweight class in September 1999.

Mosley scored consecutive 147-pound knockouts over Wlfredo Rivera and Willy Wise, and then earned a June 2000 split-decision over De La Hoya for the WBC title.

Three years later, in September 2003, Mosley earned the WBC and WBA junior middleweight (154 pounds) titles from De La Hoya by decision in their rematch.

“You can’t really say one is better than the other. At this level, they are both special. It’s proven. This will be one of the great ones,” said Mosley’s trainer, Naazim Richardson.

“On May 1, Shane will match up against one of the best athletes in the sport,” said Richardson. “Shane’s eagerness to fight sometimes hurts his negotiations. He is always so eager. ‘I’ll take the test. I’ll fight with one hand, you fight with two.’ Floyd accepted the challenge.”