Choose a back three that is good under the highball (Like Australia). Even 2 or 3 fullbacks in the back three. (e.g. Max Jorgensen who plays wing and fullback).
Gain parity at the ruck, or ideally beat them on the ground.
Have a stable scrum on defence, and clear the ball quickly on attacking scrums (like England).
If you do these three things, the Boks look vulnerable.
