The second serve follows a missed first serve. It is generally hit with more margin to avoid a double fault, but that caution can give the receiver a better chance to attack. Its effectiveness under pressure strongly affects the stability of a player's service games.

Second-serve performance often reveals technical or mental vulnerability under pressure. A player who wins regularly behind the second serve protects service games and limits break opportunities. The statistic is valuable across surfaces, opponents and high-pressure situations.

After missing the first serve, the server must use a second serve. If it sits up short, the receiver may attack immediately.