Insisting on the back-rank checkmate.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. d1c2  4... e8g8  5. e2e4  5... d7d5  6. e4e5  6... f6e4  7. f1d3  7... c7c5  8. g1f3 An extremely sharp Nimzo-Indian line, the favorable choice of  Mamedyarov. 8... c5d4  9. f3d4  9... b8d7  10. c1f4  10... d8h4  11. g2g3  11... h4h5  12. h2h4  Vallejo's choice. The Spanish GM won a couple of games with this pawn  sacrifice. 12... d7e5  13. d3e2  13... e5g4  14. e2g4  14... h5g4 All of this is very forcing, and  both players definitely knew what they were doing. 15. f2f3  15... g4h5  16. g3g4  16... h5g6  17. f3e4  17... e6e5  18. e1c1 White returns the piece at once. 18... b4c3  19. d4f5  19... c8f5  20. g4f5  20... g6a6  21. c2c3  21... d5d4  22. c3b3 A novelty at move 22! 22... e5f4  23. d1d4  23... a8d8 An important move! With the swap of a rook  pair, Esipenko weakens the white kingside. 24. b3d3 Xiong parts with  an important pawn in exchange for control over the vital open file. 24... d8d4  25. d3d4  25... f8c8 In order to weaken the second rank. 26. b2b3  26... a6a2 Best again. 27. h1d1 Xiong also plays for a win. Despite the limited material on  the board, the energy in the remaining major pieces and the insecure  position of the kings leave both sides a huge amount of tactical  possibilities. 27... g7g6 