1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. d1c2 A principled line in the  Nimzo-Indian defense which has been tested at world championship matches. 4... e8g8  5. a2a3  5... b4c3  6. c2c3  6... d7d5  7. c1g5  7... d5c4  8. c3c4  8... b7b6  9. a1d1  9... c8a6  10. c4a4 