Coach Mike Shanahan said Monday that Brian Orakpo Orakpo suffered another tear of the pectoral muscle near his left shoulder in Sunday's 31-28 loss to the St Louis Rams.
Orakpo had surgery on the same shoulder after suffering a similar injury in the final game of last season.
The Redskins now have to replace two defensive starters on a team that has allowed 63 points in its first two games.
