Nose guard is a defensive position in American football. In five-lineman situations, such as a goal-line formation, the nose guard is the innermost lineman, flanked on either side by a defensive tackle. The nose guard lines up directly opposite the offensive center, or over the center's "nose". Nose guards tend to be shorter than most other defensive linemen. They are typically very strong and their responsibility is to stop runs down the middle and draw double teams.
Extremely quick nose guards are sometimes used to shoot through the offensive line before it can react. They then sack the quarterback or make a tackle shortly after a hand off. However, this is rare because most defensive linemen are not quick enough to consistently shoot the gaps between the individual offensive linemen.
"Nose guard" is often a term incorrectly applied to the defensive tackle in a 3-4 defensive scheme. This position is known as a nose tackle. Nose guards are sometimes also referred to as middle guards.