Poison Pawn Variations
The Poisoned Pawn Variation is any of several series of opening moves in chess in which a pawn is said to be "poisoned" because its capture can result in a positional disadvantage or loss of material. The best known of these, called the Poisoned Pawn Variation, is a line of the Sicilian Defense, Najdorf Variation.
The line was most famously played in game 7 and game 11 of the 1972 World Chess Championship match between Fischer and Spassky. In both games Fischer played Black and grabbed the pawn. In the first, he reached a secure position with a comfortable material advantage but only secured a draw. In the second, Spassky surprised Fischer with a theoretical novelty and won the game after Fischer defended poorly, allowing Spassky to trap Fischer's queen and handing Fischer his only loss in the poisoned pawn variation.
The line was later taken up successfully by other leading players, including World Champions Garry Kasparov, Viswanathan Anand, and Anatoly Karpov. It remains one of the most theoretically important variations of the Sicilian Defense. In recent times, the line has become a popular battleground in computer chess, with operators trying to "out-book" each other by going progressively deeper into the different poisoned pawn lines. As a result, the line is extremely well researched. Writing in 2010, FM Graham Burgess commented that current theory suggests that the b2 pawn is "not too heavily laced with arsenic", but it would be suicidal to enter the line without specialist knowledge.