context: 1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. d1c2  4... e8g8  5. e2e4 From time to time, players with White try to exploit the complicated variations that arise from this straightforward move. The problem is that the lines are already well studied, but Keymer certainly had everything very well prepared and the risk is small. 5... d7d5 Considered by theory as the main move to equalize. 6. e4e5  6... f6e4  7. a2a3 A much rarer move than 7.Bd3 and one that had been somewhat forgotten, having not been played at the highest level for some time. Keymer was probably counting on the surprise factor. 7... b4c3  8. b2c3  8... c7c5  9. f1d3  9... c5d4  10. c3d4 