World Chess Championship Topalov, and negotiations began for a Kramnik–Topalov match to unify the title. The FIDE World Chess Championship 2006 reunification match between Topalov and Kramnik was held in late 2006. After much controversy, it was won by Kramnik. Kramnik thus became the first unified and undisputed World Chess Champion since Kasparov split from FIDE to form the PCA in 1993. Kramnik played to defend his title at the World Chess Championship 2007 in Mexico. This was an 8-player double round robin tournament, the same format as was used for the FIDE World Chess Championship 2005. This tournament was won by Viswanathan
Development of the World Chess Championship dropped the short knockout format for 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 Topalov, and negotiations began for a Kramnik-Topalov match to unify the title. The FIDE World Chess Championship 2006 reunification match between Topalov and Kramnik was held in late 2006. After much controversy, it was won by Kramnik. Kramnik thus