Colt McCoy led Washington to a field goal early in the second quarter, but he left the field limping.
He has headed to the locker room for further evaluation.
Mark Sanchez will enter the game for Washington on its next series.
McCoy is playing only because Alex Smith is out for the season with a compound fracture in his lower leg. Washington signed Sanchez after placing Smith on injured reserve.
Washington also lost another offensive guard.
The Eagles announced that defensive tackle Tim Jernigan (back spasms) is questionable to return.