Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, San Francisco Gambit

The Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, San Francisco Gambit is a chess opening classified under ECO code B30 in the Semi-Open Games family, where Black responds to 1.e4 with something other than 1...e5, including the Sicilian Defense, Caro-Kann, and Pirc. It is reached after 4 moves: 1. e4 c5 2. Nf3 Nc6 3. Bb5 Na5 4. b4. The resulting position leaves black to move.