It's actually a little worse than that. Mike Shanahan said in his Monday press conference that Moss is likely to miss 5-7 weeks with the injury.
Another injury for a Redskins team that lost Tim Hightower for the season last weekend.
Moss has 25 receptions for 301 yards and two touchdowns on the season.
Check out SB Nation's Hogs Haven for more on the injury and what the loss of Moss means.