World Chess Championship a Kasparov match, either with 2002 FIDE champion Ponomariov, or 2004 FIDE champion Kasimdzhanov. Partly due to his frustration at the situation, Kasparov retired from chess in 2005, still ranked No. 1 in the world. Soon after, FIDE dropped the short knockout format for a World Championship and announced the FIDE World Chess Championship 2005, a double round robin tournament to be held in San Luis, Argentina between eight of the leading players in the world. However Kramnik insisted that his title be decided in a match, and declined to participate. The tournament was convincingly won by the Bulgarian Veselin
World Chess Championship Anand, thus making him the World Chess Champion. Because Anand's World Chess Champion title was won in a tournament rather than a match, a minority of commentators questioned the validity of his title. Kramnik also made ambiguous comments about the value of Anand's title, but did not claim the title himself. Subsequent world championship matches returned to the format of a match between the champion and a challenger. The following two championships had special clauses arising from the 2006 unification. Kramnik was given the right to challenge for the title he lost in a tournament in the World Chess Championship