What does a chair umpire do during a match?

The chair umpire is responsible for all aspects of the match they are assigned, applying the Rules of Tennis, the Code of Conduct and the Tournament Regulations on court. They:

• call the lines (including foot faults) when no line umpire is assigned, and assign line and net umpires to positions when there is less than a full crew;
• announce points, games and sets at the end of each, and when reasonably asked by a player;
• ensure play is continuous: 25 seconds between points, a maximum 90-second changeover (none after the first game of a set or in a tie-break), and a maximum 120-second set break;
• record points, games and sets on the scorecard, sign it at the end and deliver it without delay to the Chief Umpire, Referee or other designated person (failing to sign or deliver it does not invalidate the match);
• order a replay if a line umpire cannot make a call and the chair cannot make a valid call;
• permit no coaching except as the rules allow;
• call service lets and "walking or running" foot faults, and violations such as a ball touching a player, a player touching the net, invading the opponent's court, a double bounce, an illegal carry or double hit, or a ball passing through the net;
• call for a ball change at another time if abnormal conditions warrant it, and tell the Referee when conditions justify suspending the match.

If a player asks for the chair umpire's removal, the chair relays the request to the Referee and play continues pending the decision. The chair will not remove a line umpire solely on a player's request.