One common defense to the Worm Guard is for your opponent to stand up and push your foot down into half guard (on the Worm Guard side). This puts you in a vulnerable spot to get passed, in which case you may need to force a scramble if not countered quickly. This transition to Half-X (also known as Single Leg X) allows for you to maintain control of your opponent. A key to this transition is getting a grip on your opponents pant sleeve to control their leg/ankle (control preferably in front). As soon as your opponent defends by pushing your foot down and stepping back, control the pant leg. At the same time, shoot your leg through, setting up for Half-X. Bring your heel onto your opponents hip, securing the leg and the position. Next, reach around your opponent's leg (locking it under your armpit) and pass the Worm Guard Lapel to that hand. Control the same side sleeve with the opposite hand to settle into the position.
Generally your opponent will take a grip on your lapel to balance themselves out since the leg is trapped. This is a mistake which must be taken advantage of. With the same side sleeve grip, push the arm down and pass it to the hand which is controlling the Worm Guard lapel. Once that arm is trapped, your opponent has lost their base to defend the sweep. Take a grip on the nearside lapel with your newly freed hand and place your foot that is on the opponent's hip to the mat. Shift your hips and pull down hard on the lapel and hit the hook sweep. The hook sweep elevates your opponent over your shoulder for this. Note: If opponents hands are freed you can still hit the sweep with a same side sleeve grip although it is more difficult since you cannot break their posture. Finish the sweep, landing on top and looking to attack.
Sometimes your opponent is wise and doesn't give you the sleeve grip. If this is the case, you can default to a traditional Marcelo Garcia style Traditional Half-X Sweep. To accomplish this, pull on your opponent's trapped foot, lift your hips, and shift your hips to the sweeping side at the same time, toppling your oppenent's base. In the same manner as before, end up on Top and look to either disengage to Open Guard or look to pass.