JaMarcus Russell is not practicing again on Friday, an unmistakable sign that his sudden case of right knee tendonitis is more than a minor annoyance. Russell did not finish practice Thursday because of the knee, but coach Tom Cable said it was just a precaution and that he would play Sunday against the visiting Panthers. But, if the injury is serious enough to keep him out of the last practice of the week, it is serious enough to cast doubt on Russell's ability to play in two days.