Open Guard Intermediate · No-gi first

Single-leg X: the leg is the guard

Single-leg X wraps both of your legs around one of a standing passer's, so that one leg becomes the whole guard, and the hold that sweeps them is also where a leg lock starts.

Position and problem

You are on your back, the passer is standing, and all you have is a foot pressed against their hip. They step around it, or lean on it and walk your leg down to the mat, because one foot on a hip holds distance and does nothing else. Get underneath them instead and bring one of their legs between yours, and the problem changes shape. That leg is now wrapped by both of yours and hugged to your chest, their other leg is the only thing they are standing on, and each step they take has to drag you along with it. The position is usually called single-leg X, often written SLX, and in no-gi it tends to be the place where a sweep and a leg lock begin from the same hold.

Objective

Hold one of the passer's legs with both of yours and your arms, keep them balanced on the other, and move their hips past that remaining foot to sweep them or to start an entanglement.

Core concept

Once one leg is held from the ankle to the hip, the passer has a single foot left to balance on, and a person balanced on one foot can be moved wherever that foot cannot follow. You lie on your side beneath the trapped leg with its foot hugged against your chest. One of your legs comes up from between theirs and hooks behind the trapped leg, and the other foot presses on the hip of that same leg. The hook keeps the leg bent and supplies the lift; the foot on the hip pushes it away; the arms keep the ankle from being pulled out. Between them, the trapped leg cannot step, cannot straighten and cannot retreat. The sweep follows from that. Extend the hooking leg to raise the trapped leg and push the hip back with your other foot, and their weight passes behind the only heel they have on the mat, so they sit down. From there you can come up on the trapped leg while still holding it, or keep the legs where they are and go to the foot. In no-gi the hold that sweeps is also a leg-lock position, so a passer busy defending one is often giving up the other. The names are less settled than the mechanics: depending on the source, single-leg X and ashi garami name this one position, or ashi garami is the whole family of leg entanglements with single-leg X one member of it, or the two are similar but separate positions. The shape does not change with the word. X-guard, the usual comparison, is generally played further underneath the passer with both of their legs involved; single-leg X lets the second leg go and puts all of the control on one.

Key mechanics

Hug the ankle to your chest before anything else. A foot held against your body cannot be drawn out, and while the foot stays, the hook and the hip foot have a leg to work on.
Hook behind the trapped leg from between their legs. That hook keeps their knee bent and gives you the lift; a hook that slides down to the calf leaves the knee straight and the leg free to step back.
Set the other foot on the hip of the trapped leg with your knee bent. A bent leg can still push and absorb; a leg already straight has no range left, and they can lean their weight into it.
Stay on your side facing the trapped leg, with your hips near their foot. Flat on your back, the hooks lose their angle and the passer can drop the trapped knee toward the mat through them.
Push the hip back, behind the heel of their standing foot. Their balance sits over that one foot, and a push they can hop under keeps them standing.
Come up on the leg as they sit, holding it as you rise. Releasing the ankle to stand gives the leg back, while rising with it held ends the sweep on top with the leg still under control.
Keep track of the free leg. It is their only base and their main tool, used to step over your hip foot, to push your legs off and to turn toward an entanglement of their own.

Common errors

Letting the ankle drift away from your chest, so the passer draws the foot out and steps back to a two-footed stance.
Hooking the calf instead of higher up the leg, which leaves the trapped leg straight and strong enough to kneel down through the hook.
Pushing the hip with a locked-out leg, which folds as soon as the passer leans on it.
Lying square on your back, which puts your hips under their weight and lets them sit onto your legs.
Working the sweep while ignoring the free leg, so it steps over your hip foot and the passer turns to face you from on top.

Safety

When the passer falls out of single-leg X, their trapped knee sits in the middle of the fall. The foot is held against your chest while the hip moves, so if they twist away or fall toward the trapped side, the rotation arrives at the knee with the foot fixed at one end. Keep the heel held straight rather than turned, let the ankle slide a little as they land, and treat the sweep and the leg lock as separate agreements in training: a sweep does not become a heel hook partway through unless both people agreed to leg locks before the round. From the other side, tap early to a heel that starts to turn rather than spinning out of it, because the direction of an unfamiliar rotation is easy to misread. When the passer drops the trapped knee toward the mat through your hook, your hooking knee is under their weight, so pull that leg out rather than holding it there. Heel hook and reaping rules differ between organisations, ranks and age groups.

Training progression

Static: partner stands still. Slide under one leg, hug the ankle, hook behind the leg and set the foot on the hip, then hold the shape and feel which foot they are balanced on.
Cooperative: partner walks slowly forward, back and sideways. Keep the ankle tight and the hook in place, shifting on your side so the shape survives each step.
Cooperative sweep: extend the hook and push the hip back behind their standing heel. Partner sits down under control, you come up still holding the leg, and you reset on the other leg.
Constrained: the passer may only try to free the leg, by pulling the foot out, dropping the knee or stepping over your hip foot. You may only keep the position or sweep, with no leg locks.
Positional: start in single-leg X at full resistance. You score by sweeping and coming up on the leg; the passer scores by freeing the leg and standing square.
Live rounds, with leg-lock rules agreed aloud beforehand. Pay attention to which way you were pushing each time a sweep failed, relative to the foot they were standing on.