Brad Keselowski is one of NASCAR's most intense and aggressive drivers, and it often gets him into trouble.
From roughing up other drivers on the track to post-race confrontations to pointed comments that sometimes rub people the wrong way, Keselowski has an edge that stirs controversy.
MORE: Keselowski, Gordon try to clear the air | Images from Michigan
There's a reason for that. Keselowski jokingly says he just might be bipolar.
All the great drivers are, he says.
"I believe every great driver is bipolar," Keselowski joked on Fox's prerace show Sunday.