This is a neat cooperative drill for intermediate players which focuses on groundstroke and volley control. 4 Players (A & B; and C & D) are stationed in the normal doubles positions of one-up, one-back. Players remain in these positions throughout the drill. The instructor stands off to the side near the service line.

The drill begins with the instructor feeding a ball to baseline player A in the deuce court, who hits a controlled groundstroke back to the net person C. C volleys this ball cross-court to B on the opposite service line. B volleys this ball deep to D standing on the baseline. D then hits a controlled cross-court groundstroke back to A on the baseline and the sequence continues. After several minutes, rotate the players clockwise.

You can see how many "around the horn" sequences the four players can make. Or, after one complete sequence, with the ball coming back to A, the players can then play out a point.

I like to use this drill as a measure of my students' progress by only employing it once a month or so.