Answer

Stacking is a doubles formation strategy where both partners position themselves on the same side of the court during the serve or return, rather than splitting to their 'natural' sides dictated by the score. After the ball is struck, the players rapidly shift to their preferred sides—typically so that a left-handed player can keep their forehand in the middle, or so a stronger player can dominate the forehand side. There are two main forms: server-side stacking and return-side stacking, each with specific positioning rules to avoid foot-fault violations. The primary motivation is to exploit a partnership's dominant shot patterns—particularly keeping the stronger forehand in the center where the majority of balls are exchanged. Teams also use it to hide a weaker backhand, create confusion for opponents, or maintain an advantageous formation regardless of what the score-dictated side would normally require. A key nuance that separates advanced understanding is recognizing that the server must still serve from the correct side per the score, but the partner can stand anywhere (including on the same side) as long as they don't interfere—and on the return side, similar freedom exists before the ball is struck. The trade-off is increased coordination demand and the risk of leaving court gaps if communication breaks down, making it a high-reward but execution-dependent tactic.