At a score of 6–6, a set is often determined by one more game called a "twelve point tiebreaker." Only one more game is played to determine the winner of the set; the score of the set is always 7–6 (or 6–7). Points are counted using ordinary numbering. The set is decided by the player who wins at least seven points in the tiebreak but also has two points more than his opponent. For example, if the score is 6 points to 5 points and the player with 6 points wins the next point, he wins the tiebreak and the set. If the player with 5 points wins the point, the tiebreak continues and cannot be won on the next point, since no player will be two points better than his opponent. In scoring, sometimes the tiebreak points are also included, for example 7–6 (7–5). Another way of listing the score of the tiebreak is to list only the loser's points. For example, if the score is listed as 7–6 (8), the tiebreak score was 10–8 (since 8 is the loser's points, and the winner must win by two points).
The player who would normally be serving after 6–6 is the one to serve first in the tiebreak, and the tiebreak is considered a service game for this player. The server begins his service from the
deuce court and serves one point. After the first point, the serve changes to the first server's opponent. Each player then serves two consecutive points for the remainder of the tiebreak. The first of each two-point sequence starts from the server's
advantage court and the second starts from the
deuce court. In this way, the sum of the scores is even when the server serves from the deuce court. After every six points, the players switch ends of the court; a noticeable fact is that the side-changes during the tiebreak will occur in the middle of a server's two-point sequence. At the end of the tiebreak, the players switch ends of the court again, since the set score is always odd (13 games).
An alternative tie-break system called the Coman tie-break is sometimes used by the United States Tennis Association. Scoring is the same, but end changes take place after the first point and then after every four points. This approach allows the servers of doubles teams to continue serving from the same end of the court as during the body of the set. It also reduces the advantage the elements (e.g. wind and sun) could give playing the first six points of a seven point tiebreak on one side of the court.