Mamedyarov won in Round 4 and is now tied for the lead with Ding. Radjabov and Svidler are only half a point behind the leaders.

With a victory on Monday in Round 4 of the Moscow Grand Prix, Shakhriyar Memdyarov of Azerbaijan moved to the top of the leaderboard. He shares the lead with Ding Liren of China, the sole leader after Round 3. They each have 3 points.

There were two other decisive results in Round 4: Teimour Radjabov, a compatriot of Mamedyarov’s, beat Francisco Vallejo Pons of Spain, while Ian Nepomniachtchi of Russia defeated Michael Adams of England. Radjabov’s win moved him into a tie for second with Peter Svidler of Russia, each with 2.5 points.

The Moscow Grand Prix is the second in a series of four tournaments. The top two finishers will qualify for the Candidates tournament next year to select a challenger for the World Championship.

Twenty-four of the top players in the world are competing in the Grand Prix, with 18 playing in each tournament. (Each player competes in three of the four competitions.)

A remarkable feature of the three decisive games on Monday was that all of them were won with Black.

Mamedyarov’s victory over Salem Saleh of United Arab Emirates was the most consequential for the standings. It also move Mamedyarov’s rating over 2800 for the first time.

A R Saleh Salem vs. Shakhriyar Mamedyarov
FIDE Grand Prix Moscow | Moscow RUS | Round 4.2 | 15 May 2017 | ECO: E60 | 0-1
1. d4 Nf6 2. c4 g6 3. g3 c6 4. Bg2 d5 5. Qa4 dxc4 6. Qxc4 Bg7 7. Nf3 O-O 8. O-O Bf5 9. Nc3 Nbd7 10. e3 Qc7 11. Nh4 Nb6 12. Qc5 Be6 13. b3 a5 14. Ba3 Nfd7 15. Qxe7 Rfe8 16. Qg5 a4 17. Rfc1 axb3 18. axb3 h6 19. Qf4 Qd8 20. Nf3 Nf6 21. Ne5 Bxb3 22. g4 Nbd5 23. Nxd5 Bxd5 24. h3 Nh7 25. e4 Be6 26. Bb2 Rxa1 27. Bxa1 Nf6 28. Rd1 Qa5 29. Bf3 Qa4 30. Kg2 Rd8 31. h4 Nxe4 32. Re1 Nf6 33. Nxg6 fxg6 34. Rxe6 Qxa1 35. g5 hxg5 36. hxg5 Nh5 37. Bxh5 gxh5 38. Re7 Rf8 39. Rxg7+ Kxg7 40. Qe5+ Kg6 41. Qd6+ Kxg5 42. Qg3+ Kh6 43. Qd6+ Kg7 44. Qg3+ Kf7 45. Qf4+ Ke6 46. Qe5+ Kd7 47. Qg7+ Kc8 48. Qxf8+ Kc7 49. Qe7+ Kb6 50. Qc5+ Ka6 51. f4 Qa2+ 52. Kg3 Qe2 53. f5 Qg4+ 54. Kh2 Qf4+ 55. Kg2 Qe4+ 56. Kh2 Qf3 57. Qe5 h4 58. f6 b5 White is down a pawn, but his pawn on f6 pawn is dangerous enough to secure a draw. Still, precision is required and Saleh lost his way.
59. Qg5?
59. Qe6! This would have held the draw. The f-pawn is very fast and Black will have to force a perpetual check. Note that after:
59... h3 White has
60. Qc8+ Ka5 61. Qa8+ Kb4 62. Qf8+ Kc4 63. Qg7! When Qg2, mate, has been prevented and Black has to force a perpetual before White can promote his f-pawn.  )
59... b4! Now Black's b-pawn is as advanced as White's f-pawn.
60. Qg7 Qf2+ 61. Kh3 Qe3+ 62. Kg2 Qe4+ 63. Kh2 Qxd4! Black wins another pawn and prevents f7.
64. Kh3 b3! 65. Qf7 b2! It's strange, but over the last several moves, the Black b-pawn has advanced from b5 to b2, and White's pawn is still on f6!
66. Qa2+ Kb6 67. Qb3+ Kc7 68. f7 Qf4 69. f8=R Qxf8 70. Qxb2 Qf4 Black has two extra pawns and White has no perpetual check. White is lost.
71. Kg2 c5

Radjabov had to defend against a speculative attack to join his compatriot in the winner’s circle.

Francisco Vallejo Pons vs. Teimour Radjabov
FIDE Grand Prix Moscow | Moscow RUS | Round 4.7 | 15 May 2017 | ECO: B31 | 0-1
1. e4 c5 2. Nf3 Nc6 3. Bb5 g6 4. Bxc6 dxc6 5. d3 Bg7 6. h3 Nf6 7. Nc3 O-O 8. Bf4 Nh5 9. Be3 Qd6 10. Qd2 e5 11. O-O-O b5 12. Ne2 b4 13. g4 Nf6 14. Ng3 a5 15. c4 a4 16. Rhg1 Kh8 17. Bh6 Ne8 18. Bxg7+ Kxg7 19. Nf5+?! White's position was difficult, but it was still reasonably solid. I can't imagine Vallejo thought he had enough compensation for his piece sacrifice.
19. Ne2 White is a bit worse but he can fight and has a reasonable possibility of drawing.  )
19... gxf5 20. gxf5+ Kh8 21. Qg5 Ra7! A strong defensive move. Black prepares f6 and will defend laterally along his second rank.
22. Rg4 f6 23. Qh6 Rff7! Another good move. Black can contest the g-file and force some trades.
24. Rdg1 Rg7 25. Rxg7 Nxg7!
25... Rxg7? This is tempting, trying to trade another pair of rooks, but Black would regret it after:
26. Rxg7 Nxg7 27. Ng5 When he cannot defend h7.  )
26. Ng5 Ne8! That rook on a7 proves mighty useful! Now the knight on g5 can be taken.
27. Nf3 Ba6! 28. Rg6 Rf7! 29. Ng5 It looks like something has gone wrong as Nxf7 is a tough threat to meet, but Radjabov had anticipated this problem.
29... Bxc4! Well spotted.
30. f4
30. Nxf7+ Bxf7 And Black has a decisive edge.  )
30. dxc4 Rd7 And Black will mate White.  )
30... exf4! 31. e5 Qe7! Radjabov plays accurately to the end.
32. Nxf7+ Bxf7 33. Rg1 Bxa2 34. e6 f3 35. Qf4 Bd5 The rest requires no comment.
36. Qb8 c4 37. Kd2 c3+ 38. bxc3 bxc3+ 39. Kc2 a3 40. Rg4 a2 41. Qg3 a1=N+ 42. Kd1 c2+ 43. Kd2 c1=Q+ 44. Kxc1 Qc5+ 45. Kd2 Nb3+

Nepomniatchi once again bounced back from a loss (this time in Round 3) with a victory. All four of his games in the tournament have ended decisively and all four have been won with Black.

Michael Adams vs. Ian Nepomniachtchi
FIDE Grand Prix Moscow | Moscow RUS | Round 4.8 | 15 May 2017 | ECO: B91 | 0-1
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. g3 e5 7. Nde2 Be7 8. Bg2 O-O 9. O-O b5 10. Nd5 Nxd5 11. Qxd5 Ra7 12. Be3 Be6 13. Qd3 Rb7 14. b3 Nd7 15. Nc3 Nf6 16. a4 Qd7 17. axb5 axb5 18. Ra6 Rc8 19. Rfa1 b4 20. Na4 Qc7 21. Ra2 Nd7 22. Qf1 Rcb8 23. Qd1 h6 24. h4 Bf8 25. Bf3?! I don't understand the point of this move.
25. Nb2! White should have improved his worst placed piece.  )
25... Nf6 26. Bg2 Bg2-f3-g2 is not very impressive
26. Nb2 Once again, this move was better.  )
26... Bd7! 27. Nb2 Bc6! White has a difficult time defending his pawn on e4.
28. Nc4
28. Qd3 Bb5  )
28. f3 d5  )
28... Bxe4! Black is up a pawn and with a couple accurate moves he easily consolidates his advantage.
29. Ba7
29. Nxd6 Rd8 And Black is winning.  )
29. Qe2 The computer suggests this move, but after:
29... Bxg2 30. Kxg2 d5 Black is in control.  )
29... Re8! 30. Bb6
30. Nxd6 Bxd6 31. Qxd6 Rxa7!  )
30... Qd7 31. Na5 Bxg2 32. Kxg2 Rbb8 It's funny, even in middlegames arising from a Najdorf Sicilian that seem fairly placid, and in which both sides have castled kingside, a couple of small mistakes is all it takes to change the game. Black is up a pawn and has a decisive edge.
33. Ra7 Qb5 34. Bc7 Ra8 35. Nc4 Rxa7 36. Rxa7 Qc5 37. Qa1 Ng4 38. Bb6 Qc6+ 39. f3 e4! A flashy way for Black to convert his advantage.
40. fxg4 e3+ 41. Kh2 e2 42. Qe1 d5 43. Be3 dxc4 44. Qxe2 Qe6! The rest requires no comment.
45. Qf2 Qxe3 46. Qxf7+ Kh8 47. bxc4 Qe2+ 48. Kh3 Qd1 49. g5 h5

Jon Ludvig Hammer almost won his second consecutive game as he had Anish Giri of the Netherlands in bad shape. But Giri proved to be too slippery.

Jon Ludvig Hammer vs. Anish Giri
FIDE Grand Prix Moscow | Moscow RUS | Round 4.5 | 15 May 2017 | ECO: A20 | 1/2-1/2
1. c4 e5 2. g3 c6 3. Nf3 e4 4. Nd4 d5 5. cxd5 Qxd5 6. Nc2 Nf6 7. Nc3 Qe5 8. Bg2 Na6 9. O-O Be7 10. d4 exd3 11. Qxd3 O-O 12. Qe3 Bd6 13. Rd1 Re8 14. Qd4 Bc7 15. Bf4 Qh5 16. Bxc7 Nxc7 17. f3 Ne6 18. Qf2 Ng5 19. g4 Qg6 20. Ne3 h5 21. h4 Ne6 22. g5 Nf4 23. Rd4 N6d5 24. Ncxd5 Nxd5 25. Nxd5 cxd5 26. Rxd5 Be6 27. Rd2 Rad8 28. e4 f5 29. Rxd8 Rxd8 30. Qxa7 Qf7 31. Qa5 Qd7 32. Qe5 fxe4 White is up two pawns and should win easily if he can consolidate his advantage. But his rook on a1 is still not developed and his king is a little exposed.
33. fxe4?! This loosens the White king's protection even more
33. Qxe4 Looks more natural to me. After that, I think that White should win.  )
33... Bh3! Black threatens Qg4 and it is not an easy threat for White to meet.
34. Qd5+? This forces a trade of queens, but in a simplified rook ending with only one extra pawn, White's winning chances would not have been all that great.
34. Bf3! This was the best move, but after:
34... Qd2 35. Qh2 Qd4+ 36. Qf2 Qe5 White would have had a lot of work to do. Black's pieces are very active.  )
34... Qxd5 35. exd5 Bxg2 36. Kxg2 Rxd5 37. Rf1 Rd4
37... Rd3 This was even easier but Giri's move was good enough.  )
38. Kg3 Rg4+ 39. Kh3 Kh7 40. Rf7 Rb4 41. b3 Kg6 42. Rc7 Rd4! Forcing an exchange of a pair of pawns, which improves Black's drawing chances.
43. Rxb7 Rd3+ 44. Kg2 Rd2+ 45. Kf3 Rxa2 It's now a pretty easy technical draw. The b-pawn can't go anywhere without the White king's support, but the king cannot leave the defense of the kingside pawns.
46. Rb4 Kf5 47. Ke3 Rg2 48. Kd3 Rg3+ 49. Kc2 Ke5 50. Rc4 Kd5 51. Kb2 Rh3 52. Ka3 Rg3 53. Ka4 Rh3 54. Rb4 Ke6 55. Kb5 Kd5 56. Ka5 Kd6 57. Rb7 Rxh4 58. Rxg7 Rh1 59. g6 h4 60. Rh7 Ke6 61. Rc7 h3 62. g7 Rg1 63. Rc3 h2 64. Rh3 Rxg7 65. Rxh2 Kd7 66. Rc2 Rg8 67. b4 Ra8+ 68. Kb5 Rb8+ 69. Ka4 Ra8+ 70. Kb3 Rc8 71. Rxc8 Kxc8 72. Kc4 Kb8 73. Kd5 Kb7 74. Kc5 Kc7 75. b5 Kb7 76. b6 Kb8 77. Kc6 Kc8 78. b7+ Kb8 79. Kb6

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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.