Foot sweep
Drilled with an emphasis on really hitting down to the foot instead of the shin. Also, attacking the moment the foot plants or even a half second before. Worked really well in drilling. I also started working on a followup, the foot sweep from the opposite side if the person hops over my initial attack.
In training I didn't hit it once, though... I need more grip work and to learn how to counter someone who is postured back very far.