2 Part Technique - Sometimes your opponent will hook your ankle with his foot while he holds onto a figure-four half guard, preventing you from sliding your knee through for the pass. Countering this lock is a matter of analyzing which variation of the leg entanglement he is playing; either with the "Lockdown" a la Eddie Bravo's 10th Planet system, or with the mirrored version known commonly as a "Grapevine" in wrestling. Both are dealt with similarly, in that the problem is removed by curling your foot up, slapping it down to the mat, and posting it close to his butt for Half Mount. You avoid the Lockdown by slapping to the outside of the half guard, and slapping to the inside for the Grapevine. Once you've transitioned from the Half Guard to the Half Mount, push your knee free and cross it over with the Knee Slide Pass. If you choose to keep your underhook, don't bother freeing your knee from the Half Mount and switch back to the Half Guard into the Over Under Pass. If he moves to Deep Half when you free your knee from the Half Mount, drop your knee to the mat and hit the Leg Over Pass. Don't establish Side Control until you've pummeled for an underhook first.