2.7 THE RETURN
2.7.1 The ball, having been served or returned, shall be struck so that it touches the opponent’s court, either directly or after touching the net assembly.
2.8 THE ORDER OF PLAY
2.8.1 In singles, the server shall first make a service, the receiver shall then make a return and thereafter server and receiver alternately shall each make a return.
2.8.2 In doubles, except as provided in 2.8.3, the server shall first make a service, the receiver shall then make a return, the partner of the server shall then make a return, the partner of the receiver shall then make a return and thereafter each player in turn in that sequence shall make a return.
2.8.3 In doubles, when at least one player of a pair is in a wheelchair due to a physical disability, the server shall first make a service, the receiver shall then make a return but thereafter either player of the disabled pair may make returns.
2.9 A LET
2.9.1 The rally shall be a let:
2.9.1.1 if in service the ball touches the net assembly, provided the service is otherwise correct or the ball is obstructed by the receiver or his or her partner;
2.9.1.2 if the service is delivered when the receiving player or pair is not ready, provided that neither the receiver nor his or her partner attempts to strike the ball;
2.9.1.3 if failure to make a service or a return or otherwise to comply with the Laws is due to a disturbance outside the control of the player;
2.9.1.4 if play is interrupted by the umpire or assistant umpire;
2.9.1.5 if the receiver is in wheelchair owing to a physical disability and in service the ball, provided that the service is otherwise correct,
2.9.1.5.1 after touching the receiver’s court returns in the direction of the net;
2.9.1.5.2 comes to rest on the receiver’s court;
2.9.1.5.3 in singles leaves the receiver’s court after touching it by either of its sidelines.
2.9.2 Play may be interrupted…
2.9.2.1 to correct an error in the order of serving, receiving or ends;
2.9.2.2 to introduce the expedite system;
2.9.2.3 to warn or penalize a player or adviser;
2.9.2.4 because the conditions of play are disturbed in a way which could affect the outcome of the rally.