|Moves||1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 Qb6 8.Qd2 Qxb2|
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 that begins with the moves:
after which 8.Qd2 Qxb2 usually follows, accepting the "poisoned" b2-pawn. White can also play 8.Nb3, protecting the pawn.
One of the pioneers of this line was David Bronstein, who tied the 1951 World Championship match against Mikhail Botvinnik 12-12. Bobby Fischer later became an exponent, playing it with great success.
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 with the poisoned pawn.
The line was later taken up successfully by other leading players, including World Champions Garry Kasparov, Viswanathan Anand, and even 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.
A Poisoned Pawn Variation also exists in the French Defence Winawer: 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 c5 5.a3 Bxc3+ 6.bxc3 Ne7 7.Qg4 Qc7 8.Qxg7 Rg8 9.Qxh7 cxd4 10.Ne2 Nbc6 (or 10.Kd1 Nd7). Like the Poisoned Pawn Variation in the Sicilian Najdorf, this line gives significant weaknesses for both sides and can lead to highly complex lines. White can attack on the kingside and try to exploit the passed h-pawn, while Black destroys the centre.
There is also a Poisoned Pawn Variation in the Latvian Gambit: 1.e4 e5 2.Nf3 f5 3.Bc4 fxe4 4.Nxe5 Qg5?! This variation leads to extremely sharp play, is considered rather dubious, and is thus rarely seen today. However, Graham Burgess states that it "is not utterly, clearly bad".
The variation was used in the Monk episode "Mr. Monk and the Genius".