But the World’s No. 2 ranked player survived a scare on Tuesday. In the women’s division, Paikidze, the defending Champion, also leads.

Wesley So, the No. 2 player in the world, leads the 2017 United States Championship, but only after he had a huge scare against Varuzhan Akobian in Round 6 on Tuesday. 

One of So’s main rivals, Fabiano Caruana, ranked No. 3, and the defending champion, also closed the gap after Caruana won his first game of the event, beating Gata Kamsky, a five-time United States Champion and former challenger for the World Championship. 

So has 4 points, followed by Caruana, Hikaru Nakamura, Daniel Naroditsky, Akobian, and Yaroslav Zherebukh, who are tied at 3.5 points apiece. 

In the Women’s Championship, which is being held concurrently, Nazi Paikidze, the defending champion, took over the lead after beating Irina Krush in Round 6. 

Paikidze has 4.5 points, followed by Sabina-Francesca Foisor, who has 4.

The two championships are being held at the Chess Club and Scholastic Center of Saint Louis. It is the ninth consecutive year that the club has hosted both events. The open tournament, a round-robin with 12 players, has a prize fund of $194,000. The women’s tournament, which is also a 12-player round-robin, has a prize fund of $100,000.

Caruana is obviously one of the favorites to win the championship, but he had been held in check in the first five rounds, while Kamsky was coming off a victory over Jeffrey Xiong, one of the country’s top rising stars. The game had the potential to be a real struggle, but instead it ended quickly.

Kamsky, a former prodigy, is now 42 and he has been showing signs recently of fatigue with chess. It was apparent in Round 6 as he may have mixed up his preparation as he quickly blundered away a pawn:

Caruana, Fabiano vs. Kamsky, Gata
ch-USA 2017 | Saint Louis USA | Round 6.3 | 04 Apr 2017 | ECO: B33 | 1-0
16. Nb4 Be6?? 17. Nxa6! It is next to impossible to blunder a pawn against a player rated 2800 and survive. The rest of the game was quite straightforward after this point, as Caruana wrapped up the victory.
17... O-O 18. Nb4 f5 19. O-O fxe4 20. Bxe4 Rac8 21. Rad1 White has a huge advantage.

A much bigger surprise was So’s game against Akobian. So is on an unbeaten streak of 62 games and has won several of the world’s top tournaments in recent months. During that time, he has been particularly dangerous with White. But he was never in control against Akobian. A couple of rounds earlier, playing against Alexander Onischuk, he had avoided drawing lines and managed to swindle Onischuk and win. He tried that strategy against Akobian, and it really got him into trouble: 

So, Wesley vs. Akobian, Varuzhan
ch-USA 2017 | Saint Louis USA | Round 6.1 | 04 Apr 2017 | ECO: D31 | *
Nf8 12. Nf3?! Bg4! 13. Rg1 Nf6 14. Rg3!? So undoubtedly saw but rejected the following line:
14. Qc2 Bxf3 15. Bxg6+ Nxg6 16. Qxg6+ Kd7 17. Qf5+ Ke8 But there weren't any other good options available instead of this.  )
14... g5! 15. hxg5 hxg5 16. Bxg5 Rh1+ 17. Bf1 Qc8 18. Qb3 N8h7 19. Bxf6 gxf6 20. O-O-O White has almost finished development and consolidated, after which he would be winning. But Black has one last trick:
20... Bd6! Trapping the rook!
21. Rxg4 Qxg4 22. Qxb7 Rc8 23. Qa6
23. Bd3! Was perhaps objectively the strongest move, but it wasn't appealing for White as, in the best case, he aim would be to give perpetual check. It is understandable that So did not want to do that. He probably felt that he could still manage more than just a draw.
23... Rxd1+ 24. Nxd1 Rc7 25. Qb8+! Ke7 26. Bxh7 Qxf3 27. Qg8 And White should be able to force a perpetual check.  )
23... Rc7 24. Be2 Rxd1+ 25. Kxd1 Qf5 Now the position rapidly begins to go downhill for So.
26. Nd2 Ng5 27. f4 Nh3 28. Bf3 Bb4 29. Nxd5 cxd5 30. Qb5+ Kf7 31. Qxb4

Akobian was just a move away from establishing an overwhelming edge, when he inexplicably gave up a pawn:

So, Wesley vs. Akobian, Varuzhan
ch-USA 2017 | Saint Louis USA | Round 6.1 | 04 Apr 2017 | ECO: D31 | 1/2-1/2
31. Qxb4 Qd3?? Why did Black give up the pawn on d5? There was no reason to do that.
31... Qc2+! 32. Ke1 Qc1+ 33. Ke2 Ng1+ 34. Kf2 Nxf3 And Black has an overwhelming edge.  )
31... Ng1 Was less forcing than Qc2, but it would get the job done as well.  )
32. Bxd5+ Kg7 33. Qb3 Nf2+ 34. Ke1 Rc1+ 35. Kxf2 Qxd2+ 36. Kf3 With the White bishop still on the board, it would be much harder for Black to win, so Akobian steers the game to a perpetual check:
36... Re1 37. Bc4 Qh2 38. Qb7+ Kh6 39. Qe7 Qh1+ 40. Kf2 Qh4+ 41. Kf3 Qh1+ 42. Kf2 Qh4+ 43. Kf3 Qh3+ 44. Kf2 Qh4+ 45. Kf3 Qh3+

Another surprising result was Alexander Shabalov, who had only half a point, holding Nakamura, ranked No. 6 in the world, to a draw.

Shabalov, a four-time United States Champion, is  known for his restless and imaginative attacking style. But he is now 49 and well past his prime and regularly struggles to play precisely, which has been apparent throughout the championship. But in Round 6, he played much more solidly. In the following rather calm position, he conducted a brilliant positional reorganization of his pieces, but missed a nice way to keep a positional bind:

Shabalov, Alexander vs. Nakamura, Hikaru
ch-USA 2017 | Saint Louis USA | Round 6.2 | 04 Apr 2017 | ECO: B30 | 1/2-1/2
a6 25. R3d2! Rc8 26. Bf2 Bh6 27. Rb2 f5 28. c5!? fxe4 29. fxe4 dxc5 30. Nc4! Rc6
30... cxb4 31. Nd6  )
30... Qe6 31. b5! Would be the culmination of Shabalov's plan that started with Rd2. White's domination is picturesque!  )
31. bxc5?! Shabalov could have tried a pawn sacrifice:
31. b5! axb5 32. Rxb5 It is hard to say if White is objectively better, but I prefer White's position. It is nice to be able to dominate all the center squares with pieces!  )
31... Nxc5 32. Na5 Na4 33. Nxc6 Nxb2 34. Qxb2 bxc6
34... Qxc6 Would perhaps have been a more ambitious move, but leaving the White knight on d5 does seem dangerous.  )
35. Nb6 Black might be better, but since he has a weak a-pawn, it is doubtful that he has any real winning chances in the endgame. Nakamura had been defending for a long time, so it is understandable that he did not find a way to put pressure on White.
35... Qe6 36. h3 Bg5 37. c4 h5 38. c5 Rd8 39. Rxd8 Bxd8 40. Qa1 Bg5 41. Qxa6 Qb3 42. Qa1

Aside from Caruana’s victory, there was one other decisive result in the open section: Sam Shankland (a frequent writer on World Chess), came back strong from a tough loss in Round 5 to Akobian beat Ray Robson, a teammate on the 2016 United States Olympiad team.

Shankland had a nice, little positional edge, but Robson’s demise was considerably hastened when he gaave away a pawn for no particular reason:

Shankland, Samuel L vs. Robson, Ray
ch-USA 2017 | Saint Louis USA | Round 6.6 | 04 Apr 2017 | ECO: D45 | 1-0
22. h3 a5 23. f4 a4
23... Rd8 24. Rxd8+ Qxd8 25. Qxc5 Is not an easy position for Black.  )
24. Be2 Rd8 25. Bd1!
25. Rxd8+ Qxd8 26. Qxc5 Qd2  )
25... a3? It is hard to understand what Robson was thinking at this point.
25... Rxd2 26. Qxd2 Bc6! Does look a bit awkward for Black, but that is only temporary and White has no way to exploit the situation.  )
26. bxa3 Qa5! 27. Rxd8+ Qxd8 28. Bc2 The passed White a-pawns give him a distinct edge.
28... h5 29. g4! Shankland initiates action on both flanks! Black doesn't put up much resistance as Shankland gradually overwhelms him.
29... hxg4 30. hxg4 Qc7 31. g5 Nd7 32. Kf2 f6 33. gxf6 Nxf6 34. a4 Qa5 35. Ke2 Ba6 36. Qh3 Qb6 37. a5 Qd6 38. Bd3 Bb7 39. Ng6 Nh7 40. Ne5 Nf8 41. Qh8+ Not necessary, but Shankland obviously couldn't resist playing this move.
41... Kxh8 42. Nf7+ Kg8 43. Nxd6 Ba6 44. Be4 Nd7 45. Bc6 Nb8 46. Bb5 Kf8 47. Ne4

Naroditsky, who, like me, also attends Stanford University, surprised Xiongin the opening and obtained a commanding position. But Xiong was a bit fortunate when Naroditsky overlooked an excellent opportunity to attack the Black king:

Naroditsky, Daniel vs. Xiong, Jeffery
ch-USA 2017 | Saint Louis USA | Round 6.5 | 04 Apr 2017 | ECO: D20 | 1/2-1/2
25. Rc5 Qa4 Better than a seemingly safe move like
25... Qc7 26. b4 a6 If 26... Nd7, then 27. b5, wins two pieces for a rook.
27. d5! Now the weakness on b6 is critical.
27... exd5 28. Nxd5 Qxe5 29. Nb6 Black will suffer for the rest of the game.  )
26. Qd2! Planning to go after the Black queen with Ra5, or perhaps play Nh5 and attack on the kingside.
26... Ng6 27. Ra5? Having the Black queen on a4 has considerably weakened the Black kingside, and Naroditsky fails to take advantage. After:
27. Nh5! Black would be forced to play
27... Kf8 Otherwise Bh6 would be a deadly threat. But this position already looks ominous for Black:
28. h4!? Among other moves, with the idea of playing Ng7 followed by h5, etc. The position would be quite unpleasant for Black.  )
27... Qb3 28. Nd3 Rd5! 29. Ra3 Qb5
29... Qb6 30. Nb4! Rd7 31. d5 And the Black queen would continue to be in danger.
31... Qd8 32. Nxc6 bxc6 33. d6 Nxe5 34. Bc5  )
30. Nc5 Qb6 31. Rb3 Qd8 Xiong has maneuvered the queen back to safety. The game settled down quickly after several exchanges.
32. Nxb7 Bxb7 33. Rxb7 Nxe5 34. Rcc7 Rd7 35. Rxd7 Nxd7 36. d5 Qc8 37. Rxa7 Rxa7 38. Bxa7

There was a lot of action in the women’s event in Round 6 as all the games were decisive. The most important result, which might decide the winner of the tournament, was between Krush and Paikidze. In a drawish endgame, Krush just blundered a pawn:

Krush, Irina vs. Paikidze, Nazi
ch-USA w 2017 | Saint Louis USA | Round 6.1 | 04 Apr 2017 | ECO: E15 | 0-1
Nf6 37. Nge4? Nxa2! 38. Ra1 Nxc3+ 39. Nxc3 Rd7 Black is up a pawn. It should still be a hard game to win, but Krush was clearly very upset with her blunder, and didn't put up much resistance.

Another possibly crucial match for the tournament standing was Foisor’s win against Tatev Abrahamyan. Abrahamyan, who was playing Black, appeared to be doing fine, until Foisor switched to playing on the queenside. The game ended surprisingly quickly soon afterward:

Foisor, Sabina-Francesca vs. Abrahamyan, Tatev
ch-USA w 2017 | Saint Louis USA | Round 6.3 | 04 Apr 2017 | ECO: A17 | 1-0
Nf8 30. Rb2! White shifts to the queenside, but Abrahamyan doesn't sense the change in strategy.
30... Kf7? The king is unneccesarily exposed on this square and White was already shifting away from attacking e6.
31. Reb1! Rxb2 32. Qxb2 g5 33. Bd2 Qxa4 Black's position was already unpleasant, but now it quickly falls apart.
34. Qb7! Qxd4
34... Re8 35. Qxc7+ Re7 36. Qd8 Looks unpleasant.  )
35. Qxc7+ Kg6 36. Rb7 Mate is unavoidable for Black.
36... f5 37. Qf7+ Kh6 38. Be3

The most impressive win was by Maggie Feng who calmly sacrificed a piece and then took several more moves to collect another pawn (Rh3…Rh6…Rxg6!!), all with the idea of advancing her kingside pawns. She executed this strategy with the queens and many other pieces still on the board. Most remarkable, it appears that the sacrifice was entirely justified and that there was little that her opponent, Jennifer Yu, could do about it!

Feng, Maggie vs. Yu, Jennifer R
ch-USA w 2017 | Saint Louis USA | Round 6.4 | 04 Apr 2017 | ECO: A07 | 1-0
Nb8 33. Nxf7! A brave decision!
33... Rxf7 34. Be6 Rf8 35. Bxb3 Nc6 The position is complicated. It isn't clear what White should do next. But Feng had an idea:
36. Rb1 Kb8 37. Rh3!! The plan to attack g6 seems absurd, but Black's pieces are too disorganized to fight against White's slow plan.
37... Nb4 38. Bxb4 Qxb4 39. Rh6 Na5 40. Be6 Rc7 41. Rxg6! Rh7 42. Rg8 Rxg8 43. Bxg8 The two kingside pawns give White an overwhelming advantage. The rest of the game was quite easy for her.
43... Rh8 44. Bd5 Bf8 45. Rc1 Nb7 46. Qc2 Nc5 47. g6 Rh6 48. Bf7 Rh4 49. Kg2 Bh6 50. Kg3 Bxc1 51. Qxc1 Nxd3 52. g7 Nxc1 53. g8=Q+ Ka7 54. Kxh4 Qe1+ 55. Kg5 Qxe4 56. Bd5 Qf4+ 57. Kg6 Qg4+ 58. Kf7 Qd7+ 59. Kf8 Qf5 60. Qf7+ Kb6 61. Qb7+ Ka5 62. Qc7+ Kxa4 63. f7 d3 64. Qc4+ Ka5 65. Qc5+ Ka4 66. Qxc1 Qg4

It is likely that the open section will still be decided by how the top trio — So, Caruana and Nakamura — do against the rest of the field in their remaining games. Caruana may be in the best position as he has already faced his toughest opposition. 

—————————————————————

Parimarjan Negi is an Indian grandmaster who is the second-youngest ever to earn the title (at 13 years 4 months and 22 days). Ranked No. 80 in the world, he is a junior at Stanford University. He can be found on Twitter at @parimarjan.