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 2008 (Vladimir Kramnik) had been given the right to challenge to regain his title. Its origin was in the complications in reunifying the world title in 2006. The chess world title was split between 1993 and 2006. In early 2006, FIDE had already announced the conditions for the World Chess Championship 2007: an eight-player tournament which included FIDE World Champion Veselin Topalov, but not "Classical" World Champion Vladimir Kramnik. FIDE later organized a reunification match between Kramnik and Topalov (the World Chess Championship 2006), with Kramnik to take Topalov's place in the 2007 tournament if he was to win the match.