[4] Negotiations for a match began soon after Topalov won in San Luis, but broke down after the two camps were unable to overcome substantial differences of opinion.

missed a last chance at a perpetual, after which Kramnik reached a winning endgame with two extra pawns.

The game ended with Topalov winning by forfeit, after Kramnik refused to play and his clock had been allowed to run for one hour.

Game 8 lasted 4½ hours, and resulted in Topalov's first win over the board in the match, tying the score at 4–4.

After 21 moves, the players reached a sharp, complicated, queenless middlegame with Topalov having two knights for Kramnik's rook and pawn.

Topalov spun a mating web with his knights and rook, aided by Kramnik's mistakes on moves 32 and 41.

"[26] However, Kramnik was unable to find an effective response and eventually ended up in a middlegame position where his two knights were outmatched by Topalov's powerful bishops.

Kramnik, who had struggled with a steadily deteriorating position in time trouble, resigned following Topalov's 39th move.

That left Kramnik ahead a rook for a knight and, after forcing the trade of queens, he won the endgame easily.

Towards the end, Kramnik was pressing hard for the full point, a pawn ahead in a rook and bishop endgame, but was unable to convert his advantage.

In a queen and rook endgame, with both kings open, Topalov forced a draw by perpetual check.

In the middlegame of this first game in the rapid tie-break Topalov made a pawn offer, which Kramnik accepted.

Just like in the second tiebreak game, Kramnik displayed his skill in positions where the queens have been exchanged.

[30] According to Australian GM Ian Rogers in Chess Life Online, White should still win against the superior defense 44...e5 with 45.Rab5.

On September 28, 2006, the rest day between games 4 and 5, Topalov's manager Silvio Danailov complained to the match organizers and the press about Kramnik's repeated visits to the bathroom.

He noted that the bathrooms are the only place not under audio or video surveillance, and called the frequency of the breaks "strange, if not suspicious".

[32] On September 29, 2006, the Appeals Committee, which consisted of Georgios Makropoulos, Jorge Vega, and Zurab Azmaiparashvili, determined that, although the frequency of Kramnik's visits to the toilet had been exaggerated, the private bathrooms would be closed and a common toilet opened for both players.

I am also asking you in good faith to continue your participation in this match..."[36] Later, it emerged that Kramnik's team made a procedural blunder by not filing their protest before he defaulted the fifth game.

[37] The players were invited for a meeting by Ilyumzhinov "to discuss the actual situation of the match and to solve the problems".

[38] Ilyumzhinov stated that cancelling the forfeit was possible, but that if no compromise was reached by noon on 1 October, the match would not continue.

[39] On October 1, 2006, FIDE announced that agreement had been reached that the original bathroom arrangements would be reinstated and that the Appeals Committee had resigned and would be replaced.

Later that day, FIDE announced that Game 6 would be played on October 2, with the forfeit standing and the score Kramnik 3 – Topalov 2.

He suggested several measures relating to the inspection of the bathroom and Kramnik's person meant to forestall this possibility.

[44] On October 2, 2006, more than 30 GMs, WGMs, and IMs expressed open support for Kramnik's position[45] – including former World Champions Anatoly Karpov[46] and Boris Spassky, and multiple-time challenger Viktor Korchnoi.

On October 4, Topalov's manager, Silvio Danailov, issued a press release that identified what it labeled "coincidence statistics" showing the percentage of times that Kramnik played a move that would be recommended by Chessbase's Fritz 9 chess playing software in that position (about 78% on average).

[50] GM Susan Polgar, who did not believe Kramnik was using computer assistance,[51] characterized this as "another black eye for Danailov and chess.

"[53] A statistical analysis by University at Buffalo professor Kenneth Regan found no evidence that Kramnik cheated.

[54] In an interview with the Spanish daily ABC published on 14 December 2006, Topalov alleged that Kramnik had cheated with computer help during the match, that network cables had been found in the bathroom ceiling, that threats were issued, and that he felt physically unsafe during the match.

Nine years after the match, in 2015, Kramnik stated in an interview that he does not respect Topalov as a person and will not shake hands with him.

Their rival scores after 2006 are in Kramnik's favour in classical chess (+4, -3, =3 as of May 2021[update]), and despite their rivalry, their games are still of very high quality.