Mike Munchak flagged after sideline incident with Reggie Nelson

CINCINNATI -- An unsportsmanlike conduct penalty on the offensive line coach?

Pittsburgh lost 15 yards late in the first quarter of their 18-16 AFC wild-card win overCincinnati when Steelers assistant Mike Munchak got tangled with Bengals safety Reggie Nelson, who came flying into Pittsburgh's sideline after a running play.

As Jordan Todman finished a 14-yard run out of bounds, Nelson bumped into Munchak and the two appeared to push each other. Munchak caught some of Nelson's long hair with the same hand that carried the offensive play sheet. The two were separated by officials, who deliberated, then gave Munchak a penalty. Steelers coach Mike Tomlin was not pleased.

It was difficult to tell whether anything was malicious. Nelson appeared to push Todman after the running back was well out of bounds.

This was the night's first chippy moment in a rivalry accustomed to pushing, and Munchak is a Hall of Famer who now has his first post-career penalty.

Nelson, meanwhile, was later ruled out of the game with a left ankle injury.