VII. THE COMPETITION Line Umpire had been unsighted. In that case, the point would stand  as played. Intimidating Line Umpire Case:  A serve is hit near the sideline and the receiver, hearing no  call, immediately turns around and screams at the Line Umpire. The  Line Umpire, who had signaled good, then calls and signals out. Decision:  The Chair Umpire rules the serve good based on the Line  Umpire’s original call. The Supervisor, if called, upholds the Chair  Umpire’s decision based on an official not changing his call based  on a player appeal. Note : The Chair Umpire may have to ask for the Line Umpire’s  original call if he is uncertain or disregard the Line Umpire’s call and  make the call himself. Service Order Case:  In a doubles match, Team A serves out of order. After two  points have been played, the Chair Umpire realizes the mistake. Decision:  The Chair Umpire should correct the mistake immediate - ly.  Receiving Order Case:  In a doubles match, the players on the team switched their  receiving positions during the set. When this is realized, what action  should the Chair Umpire take? Decision:  The original receiving positions of each player on that  team must be taken after the completion of the game in progress.  If error occurred during a tie break, then the receiving order shall  remain as altered until the completion of the tie break game.  7.23 Line Umpire Requirement, Positions and Calls A.Number for Matches 2) Less than a Full Complement of Line Umpires.  If less than a full complement  of Line Umpires is available, the following should be used (Sufficient Line Um - pires must be assigned in the main draw so that the Chair Umpire is not solely  responsible for calling any one line.): e)  Line umpires shall not be permitted to call through the net. d)  Chair umpire calls all “Lets,” “Foul Shots,” “Foul Strokes,” “Hindrances,” “Not  Ups” and “Touches.” c)  Base, side and center service Line Umpires call “Foot Faults” on their respec - tive lines. b)  Net judge calls all “Nets” and “Throughs” (if designated by the Chair Umpire),  measures the net height at the beginning of each set and administers the ball  changes. A net device may be authorized for use. a)  Base, side, center service and service Line Umpires call all “Outs” and  “Faults” for their respective lines. 1) Full Complement of Line Umpires.  If a Chair Umpire has a full complement of  Line Umpires, then the assignments shall be as follows: a) Seven (7) Line Umpires.  All long lines are called only up to the net. Serves  are called from the receiver’s end and the center Line Umpire returns to his  assigned sideline after the serve is put into play, i.e., there is movement  177 The approved hand signals are as follows: 1) “Out” or “Fault.”  The arm should be fully extended sideways at shoulder height,  pointing in the direction in which the ball has fallen, palm of the hand facing the  B.Hand Signals of Line Umpires  Decision:  No. If a Chair Umpire is required to umpire a match  without any Line Umpires or without a full complement of Line Um- pires, then the Chair Umpire must make the calls for the net and all  unattended lines. Case:  In ATP Tour or ATP Challenger Tour qualifying events where  approval has been granted to use less than five (5) Line Umpires  per match; may the Chair Umpire designate certain or all lines for  the players to make the calls? Players Don’t Call Lines f) Umpiring Without Line Umpires.  If a Chair Umpire is required to umpire a  match without any Line Umpires, or without a full complement of Line Um - pires, then the Chair Umpire must make the calls for the net and all unattend ed lines. If the Chair Umpire is unable to give a decision on a call or other  questions of fact, then he must order a “Let” to be played. e) Less Than Four (4) Line Umpires.  The Chair Umpire shall assign the Line  Umpires to the best advantage possible. d) Four (4) Line Umpires.  The assignments are the same as for the five (5)  man crew, except that the Chair Umpire, depending on personal preference  and court surface, selects the lines that he will call. c) Five (5) Line Umpires . The assignments are the same as for the six (6) man  crew, except that the center service Line Umpire shall move after the serve to  the side line. iv) Chair umpire calls all “Lets,” “Not Ups,” “Foul Shots,” “Touches,” “Hin - drances” and “Throughs.” iii) One Line Umpire calls each base line (2).  ii) One Line Umpire calls serves at each end of the court. i)  Three (3) umpires cover the long lines; the side service lines are called  through the net from the server’s end of court and the center service line  is called from the receiver’s end.  aa)  There is no movement during a point. b) Six (6) Line Umpires. iv) Chair umpire calls all “Lets,” “Not Ups,” “Foul Shots,” “Touches,” “Hin - drances” and “Throughs.” iii) One Line Umpire calls each base line (2).  ii) One Line Umpire calls serves at each end of the court. i)  Four (4) side Line Umpires, one of who calls the receiver’s center service  line; after the serve is put into play, this umpire returns to his assigned  side line. (The umpire calling the center service line on the receiver’s end  moves during the point when he returns to his assigned side line after the  serve is put into play.). In addition, the side Line Umpire on the receiver’s  end shall alternate calling the center service line of the “deuce” and “ad - vantage” courts, moving between points. during the point. The assignments for seven (7) Line Umpire crew are as  follows: VII. THE COMPETITION 176