Unclear : 1986 Yusupov - Timman

Continuing with Unclear Positions, the next position is from game 9 of the Yusupov - Timman Candidates Quarterfinal match played in 1986 at Tilburg in the Netherlands. Yusupov won the game, thereby clinching victory in the match.

1986 Candidates Quarterfinal Match (game 9)
Timman, Jan

Yusupov, Artur
(After 16...Qa4-a2(xP))
[FEN "r1b1r1k1/p4pbp/1p4p1/n1pPp2P/4P3/2PB1Q2/q3NPP1/2BRK2R w K - 0 17"]

Black has just accepted a Pawn sacrifice, leaving the Queen out of play on the Queenside. Annotating for Informant, Yusupov assigned his next move 17.Bh6 a '!?' symbol, meaning speculative, and indicated that his alternative was 17.Bg5 f6∞ (unclear). Timman played 17...Bh8?, overlooking the loss of the exchange with 18.Bb5 Rd8 19.Bg5.

Instead of 17...Bh8, Yusupov suggested 17...Bxh6, then 18.hxg6 fxg6 19.Rxh6 Bd7 20.Qf6 Rf8. Now White has the choice between 21.Rxg6+ with a perpetual check or 21.Qxe5 Ba4∞. This is a recurring theme: a player goes into complications with a draw in hand, planning to evaluate the position when it appears on the board and is easier to calculate.

Rybka indicates that after 21.Qxe5 Ba4, or 21...Rf7, White keeps the perpetual in hand with 22.Qg5. To play through the complete game see...

Artur Yusupov vs Jan Timman, Tilburg 1986
http://www.chessgames.com/perl/chessgame?gid=1142999

...on Chessgames.com.