LOS ANGELES -

Derek Hough may be absent from the ballroom floor Monday night when the celebrities and their professional partners return to compete in week seven of "Dancing With The Stars."

US Weekly reports the Emmy-winning dancer irritated a pre-existing back injury he endured back in season 15 with celebrity partner Shawn Johnson.

Hough will need to get medical clearance before hitting the ballroom floor.  If he doesn't, partner and Glee actress Amber Riley will perform with pro dancer Henry Byalikov.

On Monday, Hough posted a picture on Twitter of what looked like a doctor giving him injections in his back.