Professor Lucas Lepri demonstrates advanced techniques from butterfly guard when the opponent reacts to sweep attempts. After breaking a grip and crossing the opponent's arm, if the opponent lifts a leg too much, the technique transitions to a single-leg X-guard. Key details include sliding in and planting the knee near the opponent's hip, maintaining control of the sleeve. From this position, the opponent can be pushed forward for a sweep. If the opponent pulls their arm, trapping their ankle is an option. If the opponent attempts to defend by dropping their knee, Lucas places his knee strategically to prevent this. The goal is to get to a technical stand-up, securing the opponent's leg, and ultimately taking the back.