2 Part Technique - If your opponent chooses to play Open Guard from off of his back, rather than getting tangled up in his legs, dive underneath his feet and fight for control over his collar and pants. Usually, players who opt for this guard will be comfortable defending the Stack Pass into Side Control, so transition to his Back instead by driving your shoulder under his hips and flipping him over into the Turtle position. If possible, wedge your knee behind his arm as you spin around to fasten the Seatbelt and catch his arm in the Crucifix. He may even give you the hold when he tries to block your transition or goes for a takedown; answer by taking his back with the Crucifix and finishing the Rear Naked Choke.