A defensive tackle (DT) is typically the largest and strongest of the defensive players in American football. The defensive tackle typically lines up opposite one of the offensive guards. Depending on a team's individual defensive scheme, a defensive tackle may be called upon to fill several different roles. These roles may include merely holding the point of attack by refusing to be moved or penetrating a certain gap between offensive linemen to break up a play in the opponent's backfield. If a defensive tackle reads a pass play, his primary responsibility is to pursue the quarterback, or simply knock the pass down at the line if it is within arm's reach. Other responsibilities of the defensive tackle may be to pursue the screen pass or drop into coverage in a zone blitz scheme. In a traditional 4–3 defense, there is no nose tackle. Instead there is a left and right defensive tackle. Some teams, especially in the National Football League (NFL), do have a nose tackle in this scheme, but most of them do not.