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
World Chess Championship 2007 match. The FIDE World Chess Championship 2005 was also a double round robin tournament, but at the time the world title was split, with that tournament being for the FIDE world championship, and with Classical World Champion Vladimir Kramnik refusing to take part. Soon after the 2005 tournament, FIDE announced that the 2007 World Championship would also be a double round robin tournament. In 2006, FIDE announced the World Chess Championship 2006, to reunify the world chess championship. Because the organization of the 2007 tournament was largely in place, conditions of that match included: Kramnik won the 2006 match. In