Playoff Format - Round Robin

Round Robin

In a round-robin tournament, all playoff contenders play each other an equal number of times, usually once or twice (often called a "double round-robin"). This is a common format for football. In the FIFA World Cup, teams are organized into eight pools of four teams, playing each other once and ranked by points earned through wins (3 points) and draws (1 point). The top two teams advance out of each pool to the knockout phase where the top team from each pool face second-placed team from a different pool.

Continental club football tournaments have included round robin formats, such as the Copa Libertadores from the 1966 season, UEFA Champions League from the 1992/93 season, UEFA Cup from 2004/05, and the Asian and African Champions Leagues. Teams are seeded such that strongest teams should not meet until the end. In the UEFA Champions League, 32 teams are divided into eight groups of four. The group winners and runners-up advance to a two-game, total goals round, the eight third-placed teams move into the UEFA Cup third round, and the eight fourth-placed teams are eliminated.

In basketball, the Olympics also uses a round robin of the same nature, going to single elimination after the first round. The Euroleague has two double round-robin phases. The first is a "Regular Season" in which the 24 teams are divided into four groups of six (as of the 2008-09 season). The four top teams in each group advance to a "Top 16" phase in which the teams are divided into four groups of four each. The top two teams from each Top 16 group are then paired in four best-of-five quarterfinal series, with the winners advancing to the single-elimination Final Four.

Round-robin tournaments are also used in rugby union, curling, and many amateur or lower-division basketball, football, and hockey tournaments.

In 1992, the Little League World Series in youth baseball went to a round-robin tournament in the first round instead of single-elimination. In 2001, the tournament expanded to 16 teams and stayed with a round-robin for the first round, but cross-bracketed single elimination for the second round before the two winners of those games advanced to the region final. Little League used this format through 2009.

In Major League Baseball, the term "round robin" was used with regard to the possibility of a 3-way tie for the National League pennant in 1964. The Philadelphia Phillies had had a 6½ game lead with 12 games left in their regular schedule, but then lost 10 games in a row, so that the season went into its last day with 3 teams still having a chance for the NL pennant. As it turns out, the St. Louis Cardinals defeated the New York Mets on that day to take the NL pennant with no playoff; the reverse of that outcome would have left the Cardinals, the Phillies, and the Cincinnati Reds in a 3-way tie.