Negativa Derrubando gives you flexible knees and, if practiced correctly, can protect you against knee injuries in all movement disciplines and everyday life. It is performed in a lower stance with the stomach parallel to the ground and used as a sweep. If the other capoeirista is delivering a standing kick that leaves them with only one supporting leg, the extended leg can be used to hook behind that supporting leg and sweep it.
Make an entrada (step in), following the direction of the attack, so that you are side-on to your partner. Next you put both your hands on the ground and make a little jump with both feet so that the furthest leg from your partner is straightened out, and the foot is hooked behind their ankle. A variation of this move is to use the sweeping leg as a kick into the front of your partner's ankle, which can also put them on the floor.