How does the player challenge system work?
Players have unlimited opportunity to challenge, but once three incorrect challenges are made in a set they cannot challenge again until the next set. If the set goes to a tie break, players are given additional opportunities to challenge. A challenge of a line call or overrule by a player/team shall be allowed only on either a point-ending shot or when a player/team stops playing the point during a rally (returns are permitted but then the player/team must immediately stop). The Chair Umpire may only refuse the Electronic Review if he/she believes that the challenge was not made in a timely manner. Otherwise, the Chair Umpire will use the Electronic Review when there is a player/team challenge. The result of the Electronic Review is final and unappealable. The Chair Umpire may request an Electronic Review when the Line Umpire was unsighted on a point-ending shot and he/she is unable to make a decision. If the Electronic Review is unavailable for any reason, then the original line call
