3 Part Lesson -- Marcelo shows a few submissions from the back step half guard position. [I] If you back step in your opponent's half guard and find he is defending against the underhook, but leaving his neck exposed, while remaining flat on his back, be sure to take advantage of this opening and attack the north south choke. [II] Once again, you find yourself in the back step half guard position, but this time your opponent is defending against the underhook while facing you on his side. The north south choke is no longer available, but the guillotine is. After attacking the neck, use your free hand to block his arm from coming over your arm or shoulder to defend against the choke. Step over into mount and finish the submission. [III] Marcelo finishes by emphasizing the importance of surprising your opponent with your attack; upon seeing an opening, use your whole body to clamp down on the position/submission so there is little, to no, option for escape.