Our Best Tennis serve rules | The 5-Minute Guide A serve is considered a let if the ball touches the top of the net before landing in the proper service area. You're welcome to return the serve in tennis. A fault occurs if the ball strikes the net and lands outside the designated Tennis serve rules. A fault also occurs when a served ball strikes the post. Tennis players must serve the ball diagonally into the service box across the net according to the fundamental serve regulations. Visit here: https://www.ppongsuper.com/top-30-best-table-tennis-rubbers-always-fit-you/