One of the most problematic areas for half-guard players like myself is when the top guy turns his back to you (facing your legs). It is easily the safest and most stable position that you can pass from in half-guard as there aren't exactly a lot of options for the half-guard player. In fact, this is always my first option for passing someone else's half-guard and I always tell noobs to pass from this position if they encounter a guy with a dangerous half-guard. Through the past 3+ years, I have been researching, experimenting and looking for effective options to use from this position. With considerable help from my teammate (a brown belt who posts on here as Shoyoroll), my instructor Tinguinha, and some assistance from Gordo, here's some of the best options that I have discovered. For the purposes of the sweeps below, I'm playing half guard on my right side (trapping the guy's right leg). The techniques below are placed in no particular order. However, #1 and #2 have been very high percentage for me. 1) Modified Upa Sweep- This is also a great sweep option for whenever you lose the underhook battle and are cross faced by the guy (the harder the crossface the better cause he can't post that arm). This high percentage sweep usually starts with the half-guard player possesing a weak underhook (weak in the sense that the guy has turned his back to you so you can't try taking his back and the arm is in danger of getting kimura'd). I start by switching my half-guard. My left leg keeps his right leg trapped and starts stretching out his base (pulling his right leg to his right). This brings his left leg within easy reach of my right leg. I step over his left leg with my right and trapping it (just like traditional upa escape). I then post my left leg (releasing his trapped leg) and simultaneously bridging hard over my right shoulder. This is the highest percentage option I have found. It works great the majority of the time. At worst, I wind up on my knees in position to finish a double leg or single leg. 2) Rolling over sweep- This used to be a low percentage sweep for me. However, my teammate Shoyoroll modified some of its details and it's now a high percentage option for me. Shove the top guy's left arm down and to the left with your left arm. Grab the pants of his untrapped leg at the knee with your right arm and force it in the same direction as the left arm. While keeping your grips, when you start encountering resistance from him, roll over your left shoulder (important to go in this direction). His own momentum from resisting you will cause him to go over for an easy sweep. If you're wondering what to do if he doesn't push back against your pushing, simply release half-guard and take his back. 3) If he's completely facing your legs (no neck pressure at all on you), grab his head release the half-guard, bump hard towards him and immediately go flat on your stomach (killing the leverage he needs to sit up). If you pull this off, you get side control. This works best when the guy's head is up high. He can counter this sweep by ducking his head down and shifting his weight forward. 4) Half-butterfly sweep- Not a high percentage option but an option nonetheless. I find that it works better if I unlock the trapped leg (you have to use an arm to keep the leg trapped) while you try and work the sweep. Experienced guys see it coming and will resist. Nonetheless, a good 50% of the time you'll wind up in a scramble which to me is preferable than just sitting back and waiting for the guy to pass your half-guard. 5) Half-butterfly variation of #2. Same idea as #2 only you have your butterfly hook in. You shove the guy's left arm and untrapped leg down and to your left. You then use the butterfly hook to kick straight up and over your left shoulder (very important to go in that direction vs. going straight over your head). You should wind up in the other guy's guard if you sit up in time. 6) Kimura or americana options- If the top guy goes for either one of these submissions while in your half-guard. Immediately shove your left arm into your side (his arms are pinned and can't post). Grab his left leg and roll him to your left. 7) Return to closed guard/open guard- Best way to return to guard from here is to shove the guy's upper back down towards your legs. Release your half guard and start shrimping. Depending upon what he does, you wind up back in closed guard or open guard. Feedback is appreciated. Feel free to share if you have any other ideas or suggestions!