context: 1. e2e4  1... c7c6  2. d2d4  2... d7d5  3. e4e5  3... c8f5  4. c2c4 One of White's many interesting lines in the Advance Variation of the Caro-Kann. 4... e7e6  5. b1c3  5... f8b4 A good option, but not forced. 6. g1e2 A rare move. Van Foreest is a known opening specialist, and he is usually the first to show a new idea. 6... g8e7  7. a2a3 This is the idea, now the knight can capture the bishop on c3. 7... b4a5 The most natural reaction, although it's hard to say if it's better than capturing the knight. 8. b2b4  8... a5c7  9. e2g3 A new and natural move. 9... f5g6 This mistake immediately lands Black in trouble.