Final answer:
In tennis, the server is required to announce the score before serving, with their score first, followed by the opponent's score. In professional matches, this may be done by the chair umpire.
Step-by-step explanation:
During a tennis match, the server is required to call out the score before serving. This is part of the official rules in tennis and helps ensure that both players, as well as spectators, are aware of the current standing in the game. The server announces their score first, followed by the opponent's score. If the server fails to announce the score, it could result in a point penalty. However, in professional tennis matches, this duty may fall to the chair umpire who calls out the score after each point.