Player A is positioned at the baseline, deuce side, ready to serve; a basket of balls is behind him.
The coach is ready to return serve from behind the deuce baseline.
A line of cones divides each service box into two halves: wide and center (see graphic below).

Drill:
Player A will practice serving wide (between the line of cones and singles side line); if successful, the coach will return. The player will step into the ball and hit it to the open court left by the coach.
Do this until 3-5 successful combinations are achieved, then switch to the ad court.
(To place the serve wide the player should use slice serves to the deuce side and kick or flat for ad side)

Note:
– through this drill the player learns to use the wide serve for opening the court and controlling the ground-stroke placement to take advantage of the respective opening.