Starting running back Clinton Portis will be out at least this week and maybe longer due to a serious concussion he suffered last week against the Falcons.  He has carried the ball 124 times for 494 yards (4.0 ypc) with 1 TD run and he has also caught 9 passes for 57 yards (6.3 avg) with a TD grab so far this season.  Ladell Betts will get the first chance to replace Portis but he has a banged up ankle.  He has carried the ball 26 times for 91 yards (3.5 ypc) with a TD run and he has also caught 16 passes for 173 yards (10.8 avg).  If Betts were healthy the Redskins wouldn’t suffer much of a dropoff with Portis out but with him gimpy Rock Cartwright might get a chance to get in on the fun.  He has carried the ball 8 times for 27 yards (3.4 ypc) and he has also caught 4 passes for 11 yards (2.8 avg) this season.  The Redskins have also re-signed RB Quinton Ganther to help out with depth at running back while Portis is out of action.