Ben Roethlisberger's right knee injury apparently isn't serious, but Pittsburgh Steelers coach Bill Cowher wasn't ready to say if his quarterback will be ready to play Sunday in Green Bay. Roethlisberger underwent an MRI exam Tuesday, about 12 hours after the Steelers' 20-19 victory over Baltimore, and was given a preliminary diagnosis of a strained posterior capsule. The injury affects the range of motion of the knee and can be very painful. "All ligaments are fine, and we'll get a further update as the week goes on," Cowher said Tuesday. "There's nothing serious coming out of the game as we speak. ... Hopefully it's something he can continue to work through, and we'll rest him when we can and see where he is at the end of the week."