As Vassily said after game, "The game would still be complicated if Hou Yifan had played 37. Rxf6 instead of Qxe5. Hou Yifan is a strong player and she loves chess and keeps making progress. I believe she will have more successes in the future."
Hou Yifan returned the gracious acknowledgement and said that Vassily played very actively throughout the battle, putting constant pressure on white. Although there were several inaccurate moves before the time limit, the most cucial error is 37. Qxe5.
Hou Yifan - Vassily Ivanchuk
[Event "King&Queen Summit Match 2017"] [Site "Shenzhen"] [Date "2017.04.06"] [Round "2"] [White "Hou, Yifan"] [Black "Ivanchuk, Vassily"] [Result "0-1"] [ECO "C24"] [WhiteElo "2649"] [BlackElo "2732"] [Annotator ""] [PlyCount "84"] [EventDate "2017.??.??"] 1. e4 e5 2. Bc4 Nf6 3. d3 c6 4. Nf3 Be7 5. O-O d6 6. Bb3 O-O 7. Re1 Re8 { C24: Bishop's Opening: 2...Nf6} (7... Nbd7 8. c3 b5 9. Nbd2 a5 10. d4 a4 11. Bc2 Re8 12. Nf1 Bf8 13. Ng3 g6 14. h3 Bb7 15. Bg5 h6 16. Be3 {1/2-1/2 (55) Zhigalko,S (2652)-Nisipeanu,L (2687) Baku 2016}) 8. c3 Bf8 9. Nbd2 Be6 $146 ( 9... h6 10. h3 Nbd7 11. d4 Qc7 12. Nh4 d5 13. exd5 cxd5 14. dxe5 Nxe5 15. Ndf3 Nxf3+ 16. Nxf3 {1/2-1/2 (16) Negulescu,A (2464)-Vajda,L (2507) Romania 2001}) 10. Bc2 Nbd7 11. h3 h6 12. d4 Qc7 13. c4 {Black must now prevent d5.} exd4 14. Nxd4 Qb6 15. Nxe6 Rxe6 16. Nf3 Rae8 17. Nd4 Re5 18. Bf4 Qxb2 19. Bxe5 (19. Rb1 $5 {is more complex.} Qxa2 20. Rxb7 Rc5 21. Bd3 Qa6 22. Rb1) 19... dxe5 20. Nb3 Qa3 21. Qd3 a5 22. Rab1 Rb8 23. Re2 g6 24. Bd1 a4 25. Nc1 Qe7 26. Bxa4 (26. Qf3 $11) 26... Nc5 $15 27. Qc2 Rd8 28. Re3 (28. Re1 $11) 28... h5 $1 $17 29. Nd3 {Strongly threatening Nxc5 Qxc5 and Rxb7} Bh6 $1 ({Of course not} 29... Nfxe4 $6 30. Rbe1 $11) 30. Rf3 Ncxe4 (30... Nfxe4 $17 31. Re1 Nd2 32. Nxe5 Nxf3+ 33. Nxf3 Qf6) 31. Re1 $15 Rd4 {Black has compensation.} 32. c5 Nd5 ({Black should play} 32... Nd2 $17 33. Nxe5 Rc4) 33. Bb3 $11 Kg7 34. Qb2 Ndf6 35. Qc2 Qc7 36. Qe2 Nd2 {And now ...e4 would win.} 37. Qxe5 $4 (37. Rxf6 $11 Kxf6 38. Nxe5) 37... Nxf3+ $19 38. gxf3 {[#]} Qd7 $1 ({Weaker is} 38... Qxe5 39. Nxe5 Nd7 40. Nxf7 $17) 39. Nb2 $2 (39. Bc2) 39... Bf4 40. Qe7 Qxh3 {Black mates.} 41. Qxf7+ Kh6 42. Qf8+ Kg5 0-1
The score is 0.5 - 1.5 in favor of Ivanchuk
