Black wants to swap off the bishops, but on his own terms.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g1f3  3... d7d5  4. b1c3  4... c7c6  5. c1g5  5... b8d7  6. e2e3  6... d8a5 The Cambridge Springs Variation is a very solid choice. 7. c4d5  7... f6d5  8. a1c1 Nowadays more popular than 8.Qd2. 8... d5c3 The main move and a regular choice of Dreev. 9. b2c3  9... f8a3  10. c1c2  10... c6c5 Keymer is, as usual, very well-prepared and handles the opening well. 11. f1d3  11... c5d4  12. e3d4  12... b7b6  13. d3e4  13... a8b8  14. g5f4  14... c8b7  15. d1e2 An obvious move and a novelty.