Hou Yifan lost to Maxime Vachier-Lagrave in Round 4, while Levon Aronian beat Matthias Blübaum to take over the lead.

Hou Yifan finally lost in the Grenke Chess Classic. The loss, to Maxime Vachier-Lagave, dropped her from the lead after Levon Aronian beat Matthias Blübaum in Round 4 on Wednesday.

Aronian, of Armenia, has 3 points, while Hou, who is from China, is tied for second with Fabiano Carauana of the United States and Arkadij Naidistch of Azerbaijan. Vachier-Lagrave, of France, is tied for fifth with Magnus Carlsen, the Norwegian World Champion. 

Blübaum, of Germany, has struggled throughout the tournament and is in last place with half a point. Aronian had little trouble dispatching him, despite having Black.

Matthias Bluebaum vs. Levon Aronian
GRENKE Chess Classic | Karlsruhe GER | Round 4 | 19 Apr 2017 | ECO: D10 | 0-1
1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. e3 a6 5. Qc2 b5 6. b3 g6 7. Bd3 Bg7 8. Nf3 O-O 9. O-O Nbd7 10. Bb2 Bb7 11. h3?! This move is too slow, as Aronian demonstrates.
11. Rfd1 White should have put his rooks in the center as prophylaxis against any pawn breaks. White would then have a slight edge.  )
11... dxc4! 12. bxc4 c5! Black energetically opens the center.
13. Qe2
13. d5 Strategically, this move makes sense, but after:
13... bxc4 14. Bxc4 Nb6 White will lose the d-pawn.  )
13... cxd4!
13... Bxf3!? This was also possible (and the computer's choice) but I prefer Aronian's move for its simplicity.  )
14. exd4
14. Nxd4 Ne5 Would be a disaster for White because:
15. cxb5 Fails to
15... Nxd3 16. Qxd3 e5  )
14... bxc4 15. Bxc4 Nb6 White is left with an isolated queen pawn and a passive bishop on b2, while Black has a very harmonious position. The bishops on the long diagonals will prove very effective.
16. Bb3 a5! Another strong move, provoking more weaknesses by threatening both a4 and Ba6.
17. a4 Nbd5 18. Nxd5 Nxd5 19. Bxd5 White could not have been happy to make but what else can he do?
19... Bxd5 20. Ba3 Re8 21. Bc5 Bb7
21... Bxf3 This does not work as well now because of
22. Qxf3 Bxd4 23. Rad1 e5 24. Bxd4 exd4 25. Qd3 When White should be okay.  )
22. Rfb1
22. Ne5  )
22... Bxf3! Well calculated
23. Qxf3 Bxd4 White cannot pin the bishop, because:
24. Bxd4
24. Rd1 Fails to the simple
24... Bxa1 25. Rxd8 Raxd8 When Black's two rooks and extra pawn will easily overpower the White queen.  )
24... Qxd4 Black is up a pawn and converted his advantage without much trouble.
25. Rd1 Qe5 26. Qd5 Qf6 27. Rac1 e6 28. Qc5 Red8 29. Qc7 h5 30. Rxd8+ Qxd8 31. Qe5 Qd7 32. Rc4 Qd3 33. Rd4 Qb1+ 34. Kh2 Qb8 35. Rd6 Qe8 36. Qb5 Qe7 37. Rd7 Qf6 38. Qb6 Rc8 39. Qd4 Qxd4 40. Rxd4 Rc2 41. Kg3 Kg7 42. h4 Kf6 43. Rf4+ Ke7 44. Rd4 Rc3+ 45. f3 Rc2 46. Kh3 Rb2

Vachier-Lagrave ground Hou down in a long ending. Shedefended well for awhile but ultimately made a fatal error.

Maxime Vachier-Lagrave vs. Yifan Hou
GRENKE Chess Classic | 1:18:33-0:20:33 | Round 4 | 19 Apr 2017 | ECO: C65 | 1-0
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. c3 d5 6. Nbd2 dxe4 7. dxe4 O-O 8. O-O a5 9. Bxc6 bxc6 10. Nxe5 Ba6 11. Re1 Re8 12. Nxc6 Qd6 13. Nd4 Bxd4 14. cxd4 Qxd4 15. Nb3 Qxd1 16. Rxd1 a4 17. Nc5 Nxe4 18. Nxa6 Rxa6 19. Be3 h5 20. Rac1 c6 21. Kf1 Nf6 22. Bc5 Nd5 23. Rc4 Nc7 24. a3 Rb8 25. Rd2 Nd5 26. Ke1 f6 27. Kd1 Kf7 28. Kc2 Rb5 29. Kb1 g6 30. Ka2 Ke6 31. f3 Rb8 32. Re4+ Kf7 33. Rdd4 Rba8 34. Rc4 Ra5 35. Bf2 R5a6 36. Bc5 Ra5 37. g3 R5a6 38. h4 Ra5 39. Bf2 R5a6 40. Kb1 Rb8 41. Ka2 Rba8 42. g4 hxg4 43. fxg4 Re8 44. Rxe8 Kxe8 45. h5 Kf7 46. Be1 gxh5 47. gxh5 f5 48. Bd2 Nf6 49. Rc5 Black had been defending admirably in a difficult position for a long time, but now she faltered.
49... Ne4? Now Black is lost
49... Nd5 After this move, White is definitely better because of his outside passed pawn on the h-file and Black's somewhat weak queenside pawns, but Hou would retain fair drawing chances.  )
50. Rxf5+! Ke6 51. Ra5! Rxa5 52. Bxa5 Kf6 For a moment it looks like Black is holding as she will scoop up the h-pawn, but White can create a passed a-pawn and it is just fast enough.
53. b3? This is imprecise
53. Bd8+! Kg7 54. Be7! This was the way. Now the Black knight can never reach c5, and after:
54... Kh6 55. b3 The pawn will queen.  )
53... Kg5? Black repays the favor.
53... Nc5! Black prevents bxa4 and she should hold. For example:
54. bxa4 Kg5! And White would be unable to stop the Black knight from reaching c5. After:
55. Bb4 Na6! White will be unable to break through because there is no entry point for his king.  )
54. Bb4! Now White is winning again. The knight is unable to join the defense via c5, and the a-pawn cannot be stopped.
54... Kxh5 55. bxa4 Nf6 56. a5 Nd5 57. a6 Nc7 58. a7 Kg6 59. Ba5 Na8 60. Kb3 Kf7 61. Kc4 Ke7 62. Kc5 Kd7 63. Bb6 Kc8 64. Kxc6 Nc7 65. Bg1 Na8 66. Bh2 Nc7 67. Kb6 Na8+ 68. Ka6

I was quite impressed by how Vachier-Lagrave played this game. I think his level of play has fallen off a bit recently, but it is a sign of real class when a player who is off-form can still maintain an even score in a strong round robin instead of crashing and burning.

The other two games were draws. Carlsen did not manage to make any headway against Caruana, but Naiditch might lose some sleep tonight. He had Georg Meier of Germany in bad shape but let him off the hook in the time scramble.

Arkadij Naiditsch vs. Georg Meier
GRENKE Chess Classic | Karlsruhe GER | Round 4.1 | 19 Apr 2017 | ECO: D02 | 1/2-1/2
1. d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Nc6 5. Nbd2 Bg4 6. c3 e6 7. Qb3 Qc8 8. h3 Bh5 9. g4 Bg6 10. Nh4 Be4 11. f3 Bg6 12. Be2 Be7 13. Bg3 a6 14. Kf2 b5 15. Qd1 Qd8 16. a4 b4 17. a5 c4 18. Nxg6 hxg6 19. h4 Bd6 20. f4 Rb8 21. Qc2 Rb5 22. h5 bxc3 23. bxc3 Qb8 24. hxg6 Rxh1 25. Rxh1 Rb2 26. Rh8+ Ke7 27. Rxb8 Rxc2 28. Rb7+ Nd7?! Black had played some suspect moves before this point, but his position was probably still defensible. Now it no longer is.
28... Kd8! 29. Bh4 fxg6 30. Rxg7 Be7 I think Black should be able to hold a draw.  )
29. gxf7?! This is imprecise. Both sides play was marred by time pressure. For Naiditsch, that meant letting a victory slip through his grasp.
29. Bh4+! This was the strongest move. The point is that:
29... f6 Is met by:
30. Bxf6+! gxf6 31. g7 Kf7 32. Rxd7+ Be7 33. Nf3 And White has a decisive edge.  )
29... Rxd2 30. Bh4+ Kf8 31. Rxd7 Be7 32. Bxe7+ Nxe7 White is up two pawns, but the pawn on f7 cannot be saved and Black is ready to grab the pawn on c3 as well. He has plenty of counterplay. White would have to play very precisely in a complicated position to maintain his edge. Naiditch, with little time left on this clock, did not manage to do that.
33. g5?!
33. Ra7! Kxf7 34. Rxa6 Rc2 35. Rb6 Rxc3 36. g5 This was best way for white to continue.  )
33... Kxf7 34. Ra7
34. Ke1! This move was more precise. The engine claims Black is dead lost after:
34... Rc2 35. Bh5+ g6 36. Bxg6+ Kxg6 37. Rxe7 Kf5 I understand how the evaluation of this position might be unclear to the human eye. For example:
38. Rf7+ Ke4 39. Rf6! Kxe3 40. Rxe6+ Kxf4 41. g6 Rxc3 42. Rxa6 Rg3 White is winning, but this is very hard to calculate and assess from 10 moves earlier, and with little time on the clock. The Black c-pawn has the potential to be extremely annoying for White.  )
34... Rc2 35. Ke1 Rxc3 36. Kd2 Ra3 Black now has enough counterplay to hold a draw.
37. Bh5+ g6 38. Bxg6+ Kxg6 39. Rxe7 Ra2+ 40. Kc3 Ra3+ 41. Kd2 Ra2+ 42. Ke1 Kf5 43. Kf1 c3 44. Rc7 Rc2 45. g6 Kxg6 46. Ke1 Kf5 47. Kd1 Rd2+ 48. Kc1 Rd3 49. Kc2 Rxe3 50. Rc6 Rf3 51. Rxa6 Ke4 52. Rxe6+ Kxd4 53. a6 Rf2+ 54. Kb3 Rb2+ 55. Ka3 Rb1 56. Rc6 Kd3 57. a7 Ra1+ 58. Kb3 d4 59. Rc7 c2 60. Kb2 c1=Q+ 61. Rxc1 Rxa7 62. Rh1 Rc7 63. f5 Rc2+ 64. Kb3 Rf2 65. Rh3+ Ke4 66. Rh4+ Kd5 67. Rh8 Rxf5 68. Kc2 Ke4

Thursday, Hou will have a chance to right the ship as she has White against Blübaum. Aronian will also have White, against Naiditsch, Caruana will get White against Vachier-Lagrave, and Meier will have White against Carlsen, who has yet to win a game in the tournament. 

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Samuel Shankland is a United States grandmaster ranked No. 4 in the country. He is a professional player and recipient of the Samford Fellowship in 2013, the most prestigious award in the United States for young chess players. He was also a member of the team that won the gold medal at the 2016 Chess Olympiad. He is at @GMShanky on Twitter, has his own site, and is also on Facebook.