1. d2d4  1... g8f6  2. g1f3  2... b7b6  3. c2c4  3... c8b7  4. b1c3  4... e7e6  5. g2g3 This offers Black a choice  between the Queen's Indian and the Nimzo-Indian defenses. 5... f8b4  Kovalenko chooses the latter. 6. f1g2  6... b4c3  7. b2c3  7... e8g8  8. e1g1  8... f8e8 A change of heart. 9. f1e1 A useful move that prepares both e2-e4 and the maneuver Bg2-f1,  which would preserve the bishop pair.