context: 1. g1f3  1... g8f6  2. g2g3  2... c7c5  3. f1g2  3... b8c6  4. c2c4  4... d8b6 A rare move, only Black's seventh most popular choice. The idea is to prevent the d2-d4 advance. There will be a transposition to a more familiar position in a few moves. 5. b1c3 