(CNN) - Superhero actors Chris Pratt and Chris Evans are turning a friendly football feud into an epic Super Bowl bet. The stars of Guardians of the Galaxy and Captain America made the bet Tuesday on Twitter. If the Seattle Seahawks win Super Bowl XLIX, Evans must visit a Seattle children's hospital in his Captain America costume. But if the New England Patriots win, Pratt must visit a Boston pediatric cancer center dressed as Star-Lord of the Guardians. The Super Bowl is set for Feb. 1.