Safety Brandon Meriweather is helped off the field after injuring his knee in an August preseason game against the Chicago Bears. (Charles Rex Arbogast/AP)

Redskins coach Mike Shanahan said that safety Brandon Meriweather re-injured the MCL and PCL in his left knee during his pre-game collision with Aldrick Robinson in Sunday. Meriweather is expected to miss at least a week of action. He has yet to make his regular season debut.

Shanahan said Robinson was unconscious for more than a minute. He is being monitored for a concussion.

Shanahan said the Redskins are not considering working out kickers this week despite the three field goal attempts that kicker Billy Cundiff missed Sunday.

Shanahan said Robert Griffin III had his best game as a pro yesterday. The coach praised Griffin’s poise and execution.

Shanahan said Niles Paul returned kicks in place of Brandon Banks Sunday because Shanahan thought Banks was a little tentative on kickoffs. Banks sustained a hip injury suffered early in the week.

Shanahan said Pierre Garçon didn’t report any setbacks following his first action since Week 1. Shanahan said Garçon made an impact with his blocking as well as route running.

Shanahan said Josh Morgan had his best game of the season, recording four catches on four targets for 70 yards.

The head coach said “no comparison” when asked if there was a noticeable difference with the regular officials back on the job.