By the time Georges St. Pierre's fighting days are over, he hopes to be remembered as the best mixed martial artist the sport has produced. But when the 28-year-old UFC star walks away from competition, his legacy may be stamped by his ability to smash barriers outside the cage.

On Thursday, the French-Canadian welterweight champion inked a deal with Under Armour, becoming the first mixed martial artist to sign a major endorsement deal with a mainstream sports apparel company. The multi-year agreement makes St. Pierre the face -- and body -- of Under Armour's underwear line, a relationship that kicks off with an extensive media campaign this holiday season.

"I see him representing the brand across the board," said Under Armour Senior Vice President Steve Battista. "I think he's got an appeal that transcends mixed martial arts. I think he represents a whole new style of training and, really, whole new mentality about his sport."

That's exactly how manager Shari Spencer envisioned selling St. Pierre to major corporate sponsors when she took on the fighter as her sole client two years ago. In a sport whose athletes find success more with fringe than mainstream companies, Spencer felt St. Pierre embodied the kind of attributes -- natural fighting talent, a throwback demeanor, good looks and a clean reputation -- that could change the corporate world's perception of MMA.

Spencer deliberately avoided aligning St. Pierre with niche MMA brands that, despite putting money in the fighter's pockets in the short term, would have prolonged the outlaw stigma the sport yields.

"There were a lot of people sitting back saying this wasn't going to work, the brands weren't going to be there," Spencer said. "And I did turn down money within the industry. Georges was there beside me and he trusted my guidance. It wasn't so much Georges I had to convince."

The key, said Spencer, was getting St. Pierre viewed as an athlete first and fighter second. Recognizing the limited window that exists to maximize an athlete's earnings, especially those participating in sports as physically demanding as St. Pierre's, Spencer sought out the resources of Creative Artists Agency to accelerate opportunities for her client. It took about six months before CAA figured out MMA's relevance in the overall sports world and how it could work in the space. It also didn't hurt that the co-head of CAA sports, Howard Nuchow, fell in love with the combat sport after in-depth conversations with the late Tapout founder, Charles "Mask" Lewis.

In St. Pierre, Nuchow felt CAA was aligned with a mixed martial artist who could serve as a brand ambassador, someone corporations could rally behind as they entered MMA. "He's completely articulate. He's a good looking guy. He looks like he could be your neighbor, but damn, he's tough," Nuchow said of St. Pierre, who signed with CAA 13 months ago. "That is very simple to understand and to root for, and that I think creates a bigger following for MMA."

As Spencer and CAA pursued out-of-competition relationships, St. Pierre took care of business in the cage by rebounding from a stunning loss to Matt Serra in 2007 to dominate the sport's welterweight division and establish himself among the top three fighters in the world, alongside Anderson Silva and Fedor Emelianenko. That, said St. Pierre, remains the most important component to all of this. While money and sport-expanding endorsements are potentially life-changing, they won't mean much without the art he so diligently pursues.

"You need to be very careful with which brand to associate yourself with," said St. Pierre. "I never wanted to associate myself with a brand I didn't like, even if they would pay me money. It's a question of principles for me. And I think if you associate yourself with a brand that is not good for you, it doesn't give you a good image. It can hurt you in the long run when you wanted to be associated with more high-standard brands."

St. Pierre's commitment and marketability prompted Under Armour's Battista to jump at the chance to work with the fighter. If there was hesitation to enter the sport, Battista didn't show it while details of the ground-breaking endorsement deal for St. Pierre and MMA were hashed out.

"Under Armour is going to make him a face of their campaign for one of their biggest pieces of apparel," said Nuchow, whose group also brought St. Pierre to Gatorade earlier this year. "For an athlete that's really as big as you can dream about. The fact that we're talking about an athlete that happens to be an MMA fighter with a mainstream brand is not something that's happened before."

Terms of the Under Armour deal were not disclosed, though it is believed to be commensurate with packages signed by athletes in mainstream sports. Under Armour, which spends 12 to 13 percent of its annual revenue on marketing, is expects to bring in between $830 million and $835 million in revenue in 2009.

The endorsement does not call for the UFC champion to wear Under Armour during fights, though St. Pierre said that would certainly be something he'd like an opportunity to do, especially if the company decides to move forward with a line of MMA-specific performance apparel.

"I'm 100 percent sure it will help me out, and promote MMA as a legitimate sport," said St. Pierre. "For me, it's a dream come true."

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