Swiss-system Tournament - Pairing Procedure

Pairing Procedure

The first round is either drawn at random or seeded according to some prior order, such as rating or last year's performance. Players who win receive a point, those who draw receive half a point and players that lose receive no points. Win, lose, or draw, all players proceed to the next round where winners are pitted against winners, losers are pitted against losers, and so on. In subsequent rounds, players face opponents with the same (or almost the same) score. No player is paired up against the same opponent twice. In chess it is also attempted to ensure that each player plays an equal number of games with white and black, alternate colors in each round being the most preferable, and a concerted effort is made not to assign the same color three times in a row.

The basic rule is that players with the same score are ranked according to rating. Then the top half is paired with the bottom half. For instance, if there are eight players in a score group, number 1 is paired with number 5, number 2 is paired with number 6 and so on. Modifications are then made to balance colors and prevent players from meeting each other twice.

The detailed rules of how to do the pairing are usually quite complicated and often the tournament organizer has access to a computer to do the pairing. If the rules are strictly adhered to, the organizer has no discretion in pairing the round. See the link below for detailed pairing rules from FIDE.