• Electronic line calling technology has led to player challenge rules in tennis.tennis player image by jimcox40 from Fotolia.com
  
  The invention of electronic line calling technology has led to the player challenge system. The 2006 U.S. Open was the first major tournament to use electronic line calling and the technology immediately became a success. It is now used for all major tournaments. While electronic line calling improves the accuracy of line calling, mistakes can be made and players can now challenge calls.
  
  

Set Challenges

• Players are limited to three challenges per set. If the player or team challenges a call and it is incorrect, one of the challenges is lost. For example, if a player with three challenges makes an incorrect challenge, the number of challenges is reduced to two. If a player or team is correct in the challenge, no challenges are lost. Unused challenges do not carry over to the next set.
  
  

Tie-Break Challenges

• When a set ends in a tie, a tie-break game is played to determine the winner of the set. A player or team will be given one additional challenge for the tie-break game. Any challenges not used during the set can be used during the tie-break. For example, a player who has one challenge left at the end of the set and prior to playing the tie-break game, will have a total of two challenges to use during the tie-break game.
  
  

Match Tie-Break Challenges

• Occasionally, a match tie-break is played in lieu of a third set to determine the winner of the match. In this case, the tie-break is considered a set and three challenges are allowed. Any challenges remaining from the previous set do not carry over to the match tie-break.
  
  

When to Challenge

• A player must stop play immediately when challenging a line call or a chair umpire's overrule. He must also make clear to the chair umpire his intent on challenging. An electronic review takes place and the results stand and cannot be appealed. The player's request can be refused by the umpire if the player takes too long in deciding to challenge. Although not the intention of the system, players strategically use challenges to gain time when winded or to regain composure.
  
  

Special Use of the Review

• The chair umpire may request to have an electronic review of a point-ending shot. This occurs when the line umpire's view is obstructed and he cannot make the call and the chair umpire also cannot make an accurate call. This does not impact the number of challenges a player has.