The soccer star and the comedian squared off last week in a game of Just Dance 4, and the result was predictably hillarious.
Morgan appeared as a guest on O'Brien's show during a "Clueless Gamer" segment, where he reviews video games despite not having an interest in them.
Olympic gold medalist Morgan has promoted the Just Dance series for a few years, and she clearly has more experience playing the game than O'Brien.
The two started out by dancing to the popular song "Call Me, Maybe." Half way through the set, O'Brien made Morgan pause the game and explain the rules to him.
When they competed again, this time to "The Final Countdown," things were much closer, but we get the feeling that Morgan was taking it easy on her hapless foe.
Watch Morgan and O'Brien dance in the video below.