Side spin and topspin change the airflow, the pressure field changes, and the ball is forced off a straight line. Same physics every time, which is why it can be taught.
Ten yards from a wall. Forget power completely. Wrap the instep around the side of the ball and watch for rotation. Twenty balls a session.
Put a bag or a cone five yards in front of you. Bend the ball around it and back onto a mark on the wall. Add the upward brush for topspin.
Move back to 18 or 20 yards. Same run-up, same contact, longer swing path. Keep every ball under crossbar height.
