The Washington Redskins saw a once-encouraging contingency plan at quarterback fall apart a bit when interim starter Kirk Cousins left the team’s 24-13 preseason victory over the visiting Pittsburgh Steelers on Monday night with what is being described as a “mid-foot sprain.” The timeline for Cousins’s recovery wasn’t immediately known but for the time being Washington is down to just one healthy experienced quarterback — 11th-year veteran Rex Grossman — as Robert Griffin III’s quest for a Week 1 return remains uncertain. Cousins left FedEx Field on crutches and in a walking boot. X-ray results came back negative but the quarterback still will have an MRI exam Tuesday morning to provide a clearer indication of the extent of the injury. “They feel like it’s mild right now so that’s a good sign” Redskins Coach Mike Shanahan said before later adding “He’ll get an MRI tomorrow. But at least it was a good sign with the doctors today.” Meanwhile orthopedist and team consultant James Andrews observed Griffin for the first time since late July and met with team officials to discuss the quarterback’s recovery. But he wasn’t expected to make a decision on whether Griffin should open the season as Washington’s starter or wait longer before returning. The injury to Cousins overshadowed a victorious effort at FedEx Field by the Redskins who improved to 2-0 on the preseason. Despite the uncertainty hovering over Griffin and his reconstructed right knee the Redskins have expressed confidence throughout the offseason about the stability of their quarterback position because of Cousins’s presence on the roster. As a rookie the Michigan State product performed well in place of Griffin and Cousins took the bulk of the first-team snaps in the offseason to ensure his readiness if Griffin suffered a setback in his recovery.