Denver Broncos tight end Julius Thomas has left their game against St. Louis because of an ankle injury.

He left in the first quarter Sunday, and the Broncos say his return is questionable.

Backup running back Montee Ball also aggravated a groin injury that forced him to miss the last five games. He returned, dropped a pass, then was checked out again.

Thomas leads the Broncos with 12 touchdown catches this season.