1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. e2e3  4... e8g8  5. f1d3  5... c7c5  6. g1e2  6... b8c6  7. e1g1  7... d7d5  8. c4d5  8... e6d5  9. a2a3 A critical opening position. 9... c5c4 [%c_effect c4;square;c4;type;Interesting;persistent;true]