By 2002, not only were there two rival champions, but Kasparov's strong results – he had the top Elo rating in the world and had won a string of major tournaments after losing his title in 2000 – ensured even more confusion over who was World Champion. In May 2002, American grandmaster Yasser Seirawan led the organisation of the so-called "Prague Agreement" to reunite the world championship. Kramnik had organised a candidates tournament (won later in 2002 by Peter Leko) to choose his challenger. It was decided that Kasparov play the FIDE champion (Ponomariov) for the FIDE title, and the winner of this match play the winner of the Kramnik–Leko match for a unified title. However, the matches proved difficult to finance and organise. The Kramnik–Leko match did not take place until late 2004 (it was drawn, so Kramnik retained his title). Meanwhile, FIDE never managed to organise 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.