"Dennis Allen's coaching staff with the Oakland Raiders continues to take shape.

A source told FOXSports.com that running backs coach Kelly Skipper will be retained and Greg Manusky was interviewed for the defensive coordinator position. NFL Network reported Greg Knapp also has accepted the offensive coordinator position that, as first reported by FOXSports.com, was offered to him several days ago.

Manusky served as San Diego's defensive coordinator in 2010 but was fired at the end of the season. Chargers head coach Norv Turner cited a desire to improve San Diego's third-down defense as one of the reasons for the change."