Their function is to rush the passer (if they can get past the offensive linemen blocking them), and stop running plays directed at the middle of the line of scrimmage. A defensive tackle that lines up directly across from the ball (and therefore, is almost nose-to-nose with the offense's center) is often called a nose tackle or nose guard . The nose tackle is most common in the 3-4 defense and the quarter defense. Most defensive sets have from one to two defensive tackles. Sometimes, but not often, a team will employe three defensive tackles, it mainly depends on the coaching staff's gameplan.