The Under Front is a trusted defense at all levels of football, known for its strength against power run games and its ability to control the edge. While similar to the Over Front in technique names, the Under Front flips how we align the defensive line.
It’s a great option for youth and high school coaches looking to simplify gap responsibilities while staying aggressive up front.
What Is the Under Front?
At first glance, the Under Front may look similar to the Over Front. It uses the same defensive line techniques. This includes the 5, 3, 1, and 5, but the key difference is their position in relation to the offensive strength.
In the Under Front, the 1-technique lines up to the formation strength, usually to the tight end or the side with more eligible receivers. That means the 3-technique now aligns away from strength. This flips the B-gap bubble to the strong side, which is a critical shift in how the defense fits the run.
Why is this important?
By putting the B-gap bubble to the front side of the play, you’re challenging the offense to run into space you control with your Sam linebacker and defensive end. It’s especially effective for the defense, which can control the ball flow.
Defensive Line Alignment and Assignments
Here’s how the defensive line aligns in the Under Front:
- Strong-Side Defensive End: Aligns in a 5 or 6-technique depending on your preference. If you use a 6-tech, he should get hands on the tight end on every play.
- Strong-Side Defensive Tackle (1-tech): Shaded on the center toward the tight end. Controls the A-gap and often absorbs double teams.
- Weak-Side Defensive Tackle (3-tech): Outside shoulder of the weak-side guard. A disruptive player who attacks the B-gap.
- Weak-Side Defensive End (5-tech): Aligns on the outside shoulder of the offensive tackle. He’s responsible for the C-gap and setting the edge on the back side.
This is still a single-gap front, which makes it easy to teach and easier for your players to play fast.
How to Run the Under Front vs Different Looks
Teams will try to stress your defense by changing formations, running gap schemes, or using motion. Here’s how to adjust and what to teach your players:
Playing Against a Tight End
The defensive end to the tight end side can play in a 5-tech or a 6-tech. Many coaches prefer the 6-tech to ensure physical contact with the tight end, especially against teams that base their run game on strong-side power.
Here’s how to coach that 6-technique:
- If the TE blocks down = Get hands on and ride him down, looking to spill or box any pulling guard or H-back.
- If the TE blocks you = Punch and play inside, staying gap sound and maintaining leverage.
It’s uncommon to play a 7-technique in the Under Front because it creates two off-ball gaps between the DE and the tackle. That can lead to confusion in gap fits and easier angles for the offense to exploit. Keep your alignments tight and clean.
It’s common to walk down a linebacker (such as the W shown below) and play him in either a 7 technique or a true 6 technique.
Linebacker Fits and Adjustments
The Will linebacker becomes a key part of the front in the Under. He often walks up onto the line of scrimmage, acting almost like a fifth defensive lineman. He plays outside the tight end—usually in a 9-tech—and is responsible for setting the edge and spilling pullers back inside.
The Mike linebacker aligns over the strong A-gap and reads interior flow. He must be a downhill player who fits behind the Nose and fills hard on inside runs.
The Sam linebacker plays off the 3-technique on the weak side. Because the offense rarely sends double teams in his direction, he’s often left unblocked. That gives him the freedom to flow fast and make plays from sideline to sideline.
Learn more about the 4-3 structure here.
Variations of the Under Front
The Under Front offers a few key variations that you can install to handle different offensive styles without reinventing your whole defense.
G Under Front
Like in the Over Front, some coaches like to move the Nose from a 1-tech to a 2i (inside shoulder of the guard). This simple adjustment gives your defense a leverage advantage:
- It makes the center work laterally to block the Nose, which slows down combo blocks on inside zone.
- It allows your linebacker behind the Nose to scrape clean and play freely.
- It makes it harder for the offense to climb to the second level.
The G Under is especially useful when facing zone-heavy teams that rely on quick doubles and smooth climb blocks.
Heavy 5-Technique
To close the front-side B-gap bubble, many coaches use what’s called a Heavy 5-technique. This alignment tweaks the technique of the defensive end to the 1-technique side and gives him specific rules:
- If the block comes toward him = He rips inside and fits the B-gap
- If the block goes away = He surfs down the line, keeping square, and spills or boxes
This adjustment helps close out the B-gap bubble without changing the rest of the front, making it a simple and effective way to tighten up your run fits.
Install The Under Front And Its Variations
The Under Front is one of the most effective ways to defend modern run-first offenses at the youth and high school levels. It gives you:
- A five-man surface to the strong side with a tight end attached
- A strong edge presence with your defensive end
- The flexibility to adjust to zone and gap schemes with ease
Start by teaching your players the base alignments and gap responsibilities. Then layer in your variations—like G Under and the Heavy 5-technique once they’re ready.
If you want to learn what beats the under front, how to install it, and different variations, check out vIQtory Pro below.
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