Josh Koscheck out of upcoming UFC 151 bout

TUF veteran Josh Koscheck

Josh Koscheck has been forced out of his upcoming fight against Jake Ellenberger due to a bulging disc in his back. The bout was set to serve as the co-main event of UFC 151, which takes place Sept. 1 at the Mandalay Bay Events Center in Las Vegas.

According to the UFC announcement, Ellenberger will remain on the card. Another announcement concerning the fighter's new opponent is expected shortly.

Koscheck is trying to rebuild his career after dropping a five-round decision to champion Georges St. Pierre in 2010. Following the bout, a broken orbital bone kept him out of action for nearly a year. Since then, Koscheck has gone 2-1 with victories over Matt Hughes and Mike Pierce. In his last fight, Johny Hendricks stopped his momentum with a split-decision victory.

Ellenberger is also coming off a loss. The Nebraska native had won six-straight fights until running into Martin Kampmann on The Ultimate Fighter 15 Finale. During the stretch, Ellenberger scored wins over Diego Sanchez, Jake Shields and Carlos Eduardo Rocha.

In the main event of UFC 151, light heavyweight champion Jon Jones will defend his belt against former Pride FC and Strikeforce champion Dan Henderson.