The only way to play for some advantage. But this allows the central advance:
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... f8c5 Topalov's favorite development of the  bishop. 4. c2c3  4... g8f6  5. d2d3  5... a7a6  6. b1d2  6... e8g8  7. e1g1  7... d7d6  8. c4b3  8... h7h6  9. f1e1  9... f8e8  10. d2f1  10... c5a7  11. f1g3  11... c8e6 