Half Guard — Bottom

What This Is

Half guard bottom is the position in which the bottom player has both legs wrapped around one of the top player’s legs, trapping that leg between their thighs with the feet locked or crossed. The top player has effectively passed one side of the guard — their other leg is free, their upper body is over the bottom player, and they are working to complete the pass or establish side control. Half guard is not full guard that has been weakened. It is a distinct position with its own logic, its own attacks, and its own failure states.

The defining feature of half guard is the underhook battle. The top player seeks to get their arm under the bottom player’s near arm, flatten the bottom player, and advance to the pass. The bottom player fights to get or retain the underhook on the same side — the arm under the top player’s armpit on the trapped-leg side. Whoever wins the underhook controls the hip on that side, and hip control determines what each player can do next. This is not a secondary detail of half guard. It is the central contest.

Half guard uses the same invariables as full guard. The difference is that one side of the foot and knee line is already conceded before the exchange begins — the top player’s leg is trapped, so that half of the guard is partially resolved in the top player’s favour. The margin for error on the remaining connections (the underhook, the frames, and the bottom player’s hip mobility) is therefore reduced, not that different principles apply. The same rules govern both positions; in half guard, one of them is already partially lost.

The Invariable in Action

In half guard, one side of this line is already conceded. The top player’s trapped leg is between the bottom player’s legs — that side of the foot line is resolved in the top player’s favour. The bottom player’s remaining leverage is on the other side: the free leg can post, hip escape, or attempt to re-hook. The consequence of this partial concession is that the margin for error on everything else is reduced. In full guard, a weak underhook is manageable because the foot line is still fully intact. In half guard, a weak underhook combined with poor frames means the pass is very close to complete. The bottom player is operating with reduced buffer on every connection.

In half guard, elbow connection is primarily managed through the underhook. The underhook on the trapped-leg side is a direct connection to the inside of the top player’s arm that controls the shoulder and suppresses the top player’s ability to flatten the bottom player or advance the hips. Losing the underhook does not mean losing both elbow connections — the bottom player may still have a frame or wrist control on the other side — but losing the underhook without replacing it with a meaningful frame on the near side is functionally losing both connections simultaneously. The top player can flatten and advance.

Being flattened is the primary failure state in half guard. When the top player wins the underhook battle, they can drive their weight into the bottom player and press the hips to the mat. At that point, the bottom player’s hips cannot rotate, cannot drive into a sweep, and cannot generate the lateral movement needed to recover guard. The only exit from flat half guard requires first creating a frame — usually with the near elbow or forearm — to get to the side and regenerate hip mobility. It is far harder to recover from flat than to prevent being flattened. Hip mobility must be protected proactively.

The underhook battle in half guard is INV-11 made explicit. The player with the underhook on the near side controls the near hip. For the top player: underhook means they can drive the near hip down and advance toward the pass. For the bottom player: underhook means they can lift and redirect the top player’s hip, creating the angle for a sweep or back take. Every major half guard attack from the bottom — the underhook sweep, the back take, the deep half entry — begins with securing the underhook. The underhook is not one option among several. It is the condition that makes all other options possible.

Half guard frames — the forearm or elbow frames used to prevent the top player from collapsing onto the bottom player — must redirect the top player’s weight rather than absorb it. A frame driven directly into the top player’s chest will be crushed by a heavier or stronger passer. A frame placed at an angle to redirect the top player’s pressure to one side creates a deflection effect that the bottom player can use to hip escape. The frame is a redirection tool, not a barrier.

Half guard bottom is built around controlling one inside position: the trapped leg between the top player’s thighs gives the bottom player a mechanical hold on the near hip. As long as that inside position is maintained, the top player cannot advance. When the top player extracts the trapped leg — by passing the knee through — the inside position is lost and the pass is complete. The entire half guard game is a contest over whether the bottom player can maintain and exploit that inside position before the top player escapes it.

Half guard is particularly vulnerable to the crossface — the top player driving their forearm across the bottom player’s jaw to force the head away. A crossfaced bottom player is facing away from the top player, violating INV-G02: they cannot track the pass, cannot time the underhook fight, and cannot react when the top player begins advancing the knee. Defending the crossface is not merely a comfort issue — it is the prerequisite for the bottom player’s ability to function in the position at all.

The leg trap in half guard feels like the position’s anchor — the thing the bottom player must hold at all costs. But releasing the trapped leg can be the correct offensive action. When the top player’s pressure is too heavy to manage from standard half guard, voluntarily releasing the leg and sliding under the top player’s body — the deep half entry — converts a deteriorating defensive position into an active offensive one. The disconnection is not a failure; it is a resource. The bottom player who releases the leg on their own terms arrives in deep half with their hands and hips already moving. The bottom player whose leg is stripped by the top player is reacting to a loss.

Entering This Position

From Closed Guard — Guard Opened to Half

The most common unintentional entry. The top player opens the closed guard — either by standing, by prying the legs apart, or by posturing up — and the bottom player retains one leg as the guard opens. Rather than allowing the top player to pass completely, the bottom player closes the legs around the one remaining trapped leg, establishing half guard. The key here is that this should happen before the top player’s other leg is fully clear — if the top player gets both legs past, it is side control, not half guard.

From Side Control (Bottom) — Partial Guard Recovery

When the bottom player is under side control and working to recover guard, inserting one knee between themselves and the top player is the first step. If the top player’s weight prevents full guard recovery, establishing half guard is the intermediate step. The bottom player reaches the near knee in front of the top player’s near hip and closes the legs around the top player’s near leg. From here, guard recovery can continue or half guard attacks can begin.

From Mount (Bottom) — Partial Escape

A mount escape that does not complete fully will land in half guard. When the bottom player bridge-and-rolls or elbow-escapes from mount and the top player posts a leg to block the escape, the bottom player often ends in half guard with the top player’s near leg trapped. This is a better outcome than remaining in mount and should be pursued aggressively as an interim goal during mount escape attempts.

From Butterfly Guard — Hook Replaced by Leg Trap

When the top player advances from butterfly guard and the bottom player cannot maintain the double-hook configuration, trapping the near leg as the butterfly hooks are lost is a common transition. The butterfly hook becomes a half guard trap as the top player passes one side.

From Seated Guard — Leg Engagement

When the top player drives a knee through against seated guard, the bottom player can close the legs around it to establish half guard. This is a deliberate entry — the bottom player is choosing to engage the leg and create the half guard trap — rather than a fallback from a failed position.

From This Position

Half guard is primarily a position from which to attack sweeps, take the back, and transition to guard variants with more offensive geometry. The range of exits is wide, but all of them depend first on winning or maintaining the underhook.

Sweeps

Lower leg shift (scorpion): From half guard, the bottom player shifts the trapping leg from inside the top player’s thighs to outside — the foot hooks the outside of the top player’s knee. This creates the scorpion position and opens a sweep and back take dilemma. See the Scorpion / Lower Leg Shift page.

Underhook sweep: With the underhook secured on the near side, the bottom player drives forward and off the hips, sweeping the top player over the trapped leg. This requires the bottom player to come to their side first — not sweep from flat. The hip drive generates the force; the underhook controls the top player’s shoulder and prevents them from posting.

Deep half entry: When the top player pressures, the bottom player ducks under their body, hugging the trapped leg close and positioning the head near the top player’s hip. From deep half, sweep options change and the back take angle opens. See the Deep Half Guard page.

Back Takes

With the underhook, the bottom player is on their side and has the top player’s hip controlled. From here, reaching the far arm around the top player’s waist — or taking the seatbelt — gives the back. This is the highest-value exit from half guard with the underhook. The top player’s awareness of this threat is what makes the sweep and the back take work in combination: defending the back take opens the sweep, defending the sweep opens the back take.

Wrestling Up

When the underhook is strong and the top player’s base is not committed, the bottom player can come up to their knees directly — wrestling up to the single leg or double leg position. This is particularly available when the top player is light on their base in anticipation of sweeping. The underhook on one side plus the leg trap gives the bottom player a single leg entry on the trapped leg side.

Guard Transitions

To Z-guard: Insert the near knee as a shield between the top player’s hip and the bottom player’s body. The knee creates distance and a new framing structure. See the Z-Guard page.

To butterfly half: Insert one butterfly hook inside the top player’s thigh on the non-trapped side. This adds an active hook to the half guard configuration and increases sweeping leverage.

To leg entanglements: When the bottom player has the underhook and the top player’s near leg is exposed, ashi garami and cross ashi entries are available. This requires the bottom player to scoop under the top player’s body.

Submissions

Half guard is primarily a sweep and back take platform. Submissions are less common from basic half guard but not absent. The kimura (SUB-KIM-KIMURA) is available when the top player posts the far arm to prevent the sweep. The triangle (SUB-TRI-STD) can be entered if the bottom player hip escapes to create the angle and the top player’s arm is isolated. An armbar (SUB-ARM-ARMBAR) follows from the same triangle-entry angle if the triangle is not cleanly set.

Common Errors — and Why They Fail

Error: Lying flat on the back in half guard. Why it fails: INV-G05. From flat, the bottom player has no hip mobility. They cannot drive into a sweep, cannot hip escape to recover, and cannot transition to deep half. The top player simply drives the knee through and completes the pass. Correction: The first action in half guard is always to come to the side — hip escape toward the trapped leg side, come up on the elbow, and create hip mobility before attempting anything else.

Error: Letting the top player win the underhook without contesting it. Why it fails: INV-11 and INV-G03. The underhook controls the hip on that side. Without contesting it, the bottom player surrenders directional movement control and elbow connection simultaneously. The pass becomes very close to complete. Correction: Frame the near elbow and fight for the underhook immediately when half guard is established. If the underhook is lost, framing the shoulder and hip escaping away is the short-term response before re-contesting.

Error: Attempting sweeps from flat. Why it fails: Sweeps from flat half guard require the bottom player to generate upward and forward hip drive. From flat, there is no hip drive available — the hips are pinned. The attempt telegraphs and fails. Correction: Get to the side before attacking. The side position is not a sweep — it is the platform from which the sweep generates force.

Error: Using only the leg trap and ignoring the upper body connection. Why it fails: INV-G03. The leg trap alone is not sufficient to control the top player’s passing options. The top player can still flatten, crossface, and advance if the bottom player’s arms are not involved. Correction: The leg trap and the underhook or frame work as a system. If the top player is advancing despite the leg trap, the upper body connection is the variable that needs to change.

Drilling Notes

Ecological Approach

Underhook game: Both players start in half guard (top player has one leg trapped). The bottom player scores a point by sweeping to top position. The top player scores by achieving side control (clearing the leg trap). Neither player can submit. No rules on underhook positioning — both players fight for it naturally. Run for ninety seconds, switch roles. This game forces the underhook contest to occur organically and teaches the bottom player to feel when the underhook is won and lost.

Systematic Approach

Phase 1 — Hip escape to the side. Top player in half guard position, applying light pressure. Bottom player drills only the hip escape to the side — escaping flat to side position — without attempting any sweep or back take. Invariable checkpoint: are the hips elevated off the mat? (INV-G05) Ten repetitions each side.

Phase 2 — Underhook entry. From side position, the bottom player drills inserting the underhook — getting the near arm under the top player’s armpit and establishing the grip behind the top player’s back. Top player provides moderate resistance to the underhook insertion. This is the single most-drilled movement in half guard. Twenty repetitions.

Phase 3 — Underhook sweep. With the underhook in place, the bottom player drills the forward hip drive to complete the sweep. Top player provides resistance and attempts to post. The bottom player learns to time the drive to the moment the underhook is fully seated and the top player is not fully based. (INV-13)

Phase 4 — Underhook game (ecological), as above.

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