Multiple sources told FOXSports.com that Georgia outside linebacker/defensive end Justin Houston and Iowa defensive lineman Christian Ballard failed drug tests at the NFL Scouting Combine in February. Both players tested positive for marijuana, the sources said.

Houston, an early entry junior, is projected in some mock drafts as a late first-round draft choice. The 6-foot-3, 270-pound Houston had 67 tackles and 10 sacks last season for the Bulldogs as a rush linebacker.

Houston's athleticism and pass-rush skills make him especially appealing as an outside linebacker for NFL teams that use a 3-4 defensive scheme.