Tom Brady may have failed to score yesterday against the Miami Dolphins, but the heralded New England Patriots quarterback feels that his chances are better in court. He is suing Yahoo! (NASDAQ:YHOO), claiming that the portal is using his likeness in ads for its fantasy football service without his permission.

Brady is no stranger to being a pitchman. He's been in televised ads for Visa and has teamed up with John Madden to promote NFL coverage on Sirius (NASDAQ:SIRI). He may not be as visible as Peyton Manning (and, really now, isn't Manning somehow a part of every other commercial on TV these days?), but he's obviously a marketable entity who expects to receive compensation when his mug is used in ads. The ads in question ran online through Yahoo! and in print form in Sports Illustrated.

The lawsuit claims that fantasy football is a $4 billion a year business and that Yahoo!'s platform supposedly draws 4.4 million users; Brady feels that he is being cheated, even though he is one of five NFL players featured on the ad.

It's a tricky situation. The NFL and Yahoo! are digital partners. Back in September, they teamed up to offer streamed gridiron games to the world outside North America. Yahoo! has been offering fantasy football for a few years now, rivaling the premium service over at CBS's (NYSE:CBS) Is Yahoo! paying the NFL for the rights to its NFL services? If so, does that include the right to use specific players in its ads? The decision is now up to the U.S. District Court in Los Angeles.

Yes, fantasy football is so big that one star player has even suggested that fantasy league owners should pay the players when they produce on the field. It's also a fickle world; Brady and Randy Moss are featured in the ad, but neither one is likely to make the prolific cut next season -- Brady's doing just fine, but he does have six other quarterbacks with more fantasy points this season.

You also have companies like Electronic Arts (NASDAQ:ERTS) that will pay licensing rights to the league and players to feature NFL teams in their football video games. The gray areas may limit damages in this unique case, but it's easy to understand Brady's position. Overexposure, even for an ad-happy Manning, can ultimately be detrimental to a player -- especially once he hangs up his cleats for good.

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Longtime Fool contributor Rick Munarriz is a frequent Yahoo! visitor, but he does not own shares in any of the companies mentioned in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.