6. ... d3!? seems to be the only correct answer in the position. 6. ... dxc3?! gives white open lines and attacking chances. 6. ... Qf6 also isn't very good because of 7. b4! followed by 8. b5, and if black plays 7. ... dxc3?, then he loses after 8. bxc5! c2 (Otherwise white plays Qc2 and black is lost.) 9. Qxc2 Qxa1 (The only move from the material point of view, black would have been in a big material disadvantage.) 10. Bb2 Nb4 11. Qb3 Qxb1 12. Rxb1 Nc6 13. Bxf7+ with a totally winning position for white .

Position after 16. ... Kxf7: Black is a exchange down and a pawn up, but he has the better position. His bishop pair dominates a big part of the board, the white square complex on the queenside and the center is quite weak, and white has not yet mobilised his rooks.

18. c4 wouldn't have been very good. For example: 18. ... Rd8 19. Rad1 Ba5 20. Bc1?! Bxd2 21. Rxd2 Rxd2 22. Bxd2 Bxc4 23. Rc1 Bb5 and black still seems to hold his advantage.

19. Ne4: Looking for an exchange, to simplify the position. However, this move allows black to threaten the position of his white squared bishop become even stronger, together with the win of a tempo.

20. Nc5: once again seems like the best move. 20. Nxf6? looks like a quite big blunder, after 20 ... gxf6 black's e pawn is consolidated, he can advance his f-pawn whose strenght will be even increased in combination with the bishop which pressures on f2, while the other bishop guards the f1 square. The ideal postion of black's pawns would be the following: c4, e4 and the f-pawn on f4 to prepare e3.