Two players at the net, B and C. One player at the baseline, A, on the other side of the net. A feeder (F) sends balls to A to begin each rally. 
Player A has 90 seconds to win as many points as she can against the team B-C. Every time a point is over, the feeder puts another ball in play by sending it to A. After 90 seconds, the players rotate places clock-wise and the time starts again for the new player.
Once every player finishes the 90 seconds against the other two players, they compare the scores with each other. The player with the highest number of points won in 90 seconds wins 1 game.
Play again until one of the players wins 2 (or 3) games.
Note: Excellent conditioning drill for the single player.