Interzonal Tournament

The Interzonal Tournament was a stage in the International Chess Federation's (FIDE) World Championship qualification system for much of the second half of the twentieth century. Interzonal means between zones. Players arrived through Zonal tournaments associated with different geographic regions, then met for places in the next stage.

The basic route was Zonal, Interzonal, Candidates, and world-title match. Leading Interzonal finishers advanced to a Candidates tournament or Candidates matches, which selected the world champion's challenger. The formal structure began with FIDE's first championship cycle after the 1948 championship. Formats changed over time, including large round-robins, several parallel Interzonals, and different numbers of qualifying places.

Interzonal was not another name for Candidates. It filtered players before that final challenger-selection stage. Palma de Mallorca 1970, for example, was a 23-round tournament offering six Candidates places and was the last Interzonal held as one all-play-all section. The Interzonal and Candidates route later formed part of Garry Kasparov's path to Karpov-Kasparov 1984. The system ceased to be the standard route during the 1990s.