St. Petersburg Variation, Fischer Variation

The Fischer Variation is Black's reply 5...Ba6 to the knight development 5. Ne2. The bishop targets c4, which the f1-bishop cannot easily defend while the e2-knight blocks it, and Black often follows with ...d5 to exchange the light-squared bishops and claim the light squares. Keres, Bronstein and Smyslov helped build its theory, and Fischer used it with success. White's main answers are 6. a3, Botvinnik's preference and by far the most common choice, which asks the b4-bishop to commit, and Reshevsky's 6. Ng3, preparing e4.