The player starts by standing behind the doubles alley on the advantage side.
The coach feeds regular deep balls to the backhand side, and the player aims to hit the ball down the line in between the doubles alley.
Hitting into the alley requires almost the same technical motion all the time so it is a great exercise to make the backhand action feel easy for the player.
Placement is one of the most important skills in tennis. The player has to be able to put the ball into the desired area even under pressure. In this specific exercise, the player has a visual target that will help them monitor their success or failure in this drill.
For more advanced players, the coach can feed different balls such as short or deep, or they can vary the spin and pace to make it more difficult for the player to control.