As it turns out, Clinton Portis groin injury is more serious than he expected. During his media session today, Mike Shanahan said Portis will miss 4-6 weeks with the groin injury.
Shanahan: Portis has third degree separation of groin. 4 to 6 weeks.
As Rich Campbell noted, Shanahan said the groin was separated from the bone. Shanahan called the injury a "temporary setback," and said it's particularly disappointing because Portis was playing well.
This means Ryan Torain will certainly start for the foreseeable future, and according to Redskins Insider, it likely means Keiland Williams will be promoted from the practice squad, though that has not happened yet. The Redskins did just add running back Javarris James to the practice squad today, as Hogs Haven notes.