Hurting: Right guard Chris Chester sprained his left ankle during practice Monday, but coach Mike Shanahan said he won’t need an MRI. However, Shanahan was not sure of the severity of the injury.

If Chester doesn’t practice Tuesday it’s hard to imagine him being ready for the preseason opener vs. Buffalo on Thursday. That would leave Washington with three backups starting. Buffalo recorded 10 sacks in a win vs. Washington last year, though the bulk of them occurred because quarterback John Beck held the ball too long.

RG3 Update: Robert Griffin III did not have his best practice. In fact, it was one of his sloppiest as he was inaccurate with his passes and was intercepted once by corner Josh Wilson. Griffin even had a ball slip out of his hands as he went to throw from the pocket.

Even in warm-ups, Griffin is not the most accurate passer. He’ll throw three good passes in a row followed by three that are off target.

Injury report: FB Darrel Young (hamstring) and RB Lance Lewis (groin) are unlikely to play vs. Buffalo. But Shanahan said he’s not sure who else will miss (aside from LG Kory Lichtensteiger and RT Jammal Brown). WR Anthony Armstrong (shoulder) returned to practice, but did not participate in full-team drills.

John Keim covers the Redskins for the Washington Examiner. Follow him on Twitter@CBSSportsNFLWAS.