20 August 2016

Commentary: 2016 U.S. Championship, Round 11 (Krush - Paikidze)

This last commentary game from the 2016 US Championship is the decisive round 11 encounter between GM Irina Krush and IM Nazi Paikidze in the Women's section.  (Original ChessBase commentary can be found here.)  Krush by this point in the tournament, with 6 points, was out of the running, while Paikidze had to win as Black in order to catch up to WGM Tatev Abrahamyan.

As with many games, knowing the context is important to understanding the choices made by the players.  Paikidze as Black could not afford to be passive, while Krush as White had no need to strive for a win.  This dynamic I think helped shape the game from the start in terms of the opening choice (a King's Indian Attack).  White with 17. f4 provokes a complex middlegame with a number of tactical ideas lurking in the variations - mostly to Black's benefit.  Black in response sacrifices a pawn and has the initiative for almost the entire game, although Krush at one point had fought back to near-equality.  Paikidze's play illustrates some important tactical and positional concepts for improving players and the factors involved are well worth studying.

Krush, Irina (2465) - Paikidze, Nazi (2346)

Result: 0-1
Site: Saint Louis USA
Date: 2016.04.25
[...] 1.¤f3 ¤f6 a noncommital response to White's first move, while ruling out an immediate e4 as follow-up. 2.g3 d5 3.¥g2 c6 4.O-O ¥g4 this is slightly more challenging than the other standard move developing the bishop to f5. 5.d3 continuing with the standard plan of the King's Indian Attack setup. White will eventually play e4. 5...¤bd7 the knight needs to be developed in any case, and this provides the option of supporting an ...e5 push. 6.h3 ¥h5 7.£e1 getting off the h5-d1 diagonal and behind the e-pawn. 7...e5 played the vast majority of the time, forming a pawn duo in the center. (7...e6 is certainly possible, but is unambitious and drawish.) 8.e4 dxe4 not necessarily obligatory, but almost always played. The following game shows how problems can develop for Black by delaying it.
8...¥d6 9.exd5 ¥xf3 10.¥xf3 ¤xd5 11.¤c3 ¤xc3 12.bxc3 O-O 13.¦b1 £c7 14.¥d2 f5 15.£e2 ¦ae8 16.¥g2 ¢h8 17.£h5 ¥c5 18.¥g5 ¥b6 19.¦b4 ¦e6 20.¦h4 h6 21.d4 f4 22.gxf4 exd4 23.£g4 ¦g6 24.¥e4 ¦xf4 25.£xf4 £xf4 26.¦xf4 ¦xg5+ 27.¢h1 ¤f6 28.cxd4 ¥xd4 29.¦d1 ¥b6 30.¥f5 ¢g8 31.c4 ¥c7 32.¦f3 b5 33.cxb5 cxb5 34.¦b1 a6 35.¦c1 ¥e5 36.¦c6 ¢f7 37.¦xa6 ¥d4 38.¦d6 ¥c5 39.¦c6 ¥e7 40.¦c7 g6 41.¦e3 1-0 (41) Movsesian,S (2695)-Zontakh,A (2546) Loo 2013
9.dxe4 ¥c5 developing the bishop to its most effective diagonal. 10.a4 a5 preventing a b4 advance. 11.¤a3 actually the most common move played here, but scoring only 46 percent for White in the database. The point is to transfer the knight to c4. 11...O-O 12.¤c4 £c7 protecting e5 and connecting the rooks. 13.¥d2 b6 the obvious move, to ensure the a5 pawn is protected and Black's pieces are not tied down to it. 14.¤h4 intending to go to f5, but the knight ends up stuck here for a long time before exchanging itself for the bishop on g6. 14...¦fe8 developing the rook, which was doing nothing on f8. 15.¢h1 getting off the a7-g1 diagonal and preparing to push the f-pawn. 15...¥g6 anticipating the push g4 and pressuring e4, essentially inviting the following exchange. 16.¤xg6 hxg6 although White now has the two bishops, the individual minor piece trade is a fine idea for Black. Her light-square bishop was not doing anything very important and the White knight on the kingside otherwise could effectively support a pawn advance and/or could go to f5. 17.f4 a natural move, but perhaps White could have taken some more time to prepare it. Black is able to launch a counterstroke on the queenside. 17...b5 the tactics work in Black's favor if White accepts the pawn sacrifice. 18.¥xa5
18.¤xa5 is inferior, as the Na5 is out on a limb and its protectors can become overloaded, while Black has multiple other threats. 18...exf4 19.axb5 f3 20.¦xf3
20.¥xf3 cxb5³ and now Black can threaten the g3 and c2 pawns after ...Bd6.
20...cxb5 21.¦b3 ¥d6³22.¦e3 (22.¦xb5?22...¤c5µ)
18...£c8 19.axb5 cxb5 20.¤d2 the engine assesses the position as equal, as White's pieces are not as well coordinated as her opponent's and Black can start making threats along the e-file. 20...exf4 21.gxf4 ¤d5 a key move in the sequence, as the knight takes advantage of the pinned e-pawn to use d5 as an outpost and threaten to go to e3. 22.¦f3 defending the e3 square, albeit awkwardly.
22.b4!? is a recurring idea in this position that the engines identify. White at least temporarily gives back the pawn in order to better activate her pieces and deflect Black's threats. For example 22...¤xb4 23.£b1 ¤c6 24.£xb5 ¤xa5 25.¦xa5 ¦xa5 26.£xa5 ¤f6
22...f5?! this invites the advance of the e-pawn, which essentially solves White's problems with it.
22...¤7f6 would increase the pressure and not allow for the advance, as if 23.e5?!23...¤h5µ and now the f-pawn is under fire.
23.e5 g5 evidently this was Paikidze's idea, to pressure the e-pawn by undermining its support. White is faced with some complex choices. 24.fxg5? this was unnecessary and justifies Black's play.
24.£d1 would get the queen out of the pin first and improve on the idea. 24...gxf4? (24...¤7b6 25.fxg5 ¦xe5 26.b4 ¥xb4 27.¥xb4 ¤xb4 28.¦xa8 ¤xa8 29.¦b3±) (24...¤xf4?25.¦xf4 gxf4 26.¥d5+ ¢f8 27.£h5±) 25.¤c4 bxc4 26.£xd5++⁠−
24.b4!? has similar ideas as in the variation above. The hanging Nd5 and the open long diagonal give White some tactical possibilities and Black has to be careful.
24...¤xe5 Black now takes over the initiative. The two centralized knights in combination with the Re8 and Bc5 can make a variety of threats in this wide-open position. 25.¦f2? preserving the rook in this way just leads to more trouble for White. The engines suggest a positional exchange sacrifice. (25.£g3!?25...¤xf3 26.¥xf3µ) (25.¦f1 ¤e3µ) 25...¤e3−⁠+ it's clear by this point that for the investment of a pawn, Black's pieces are now dominating the game. This is a more positional road to victory.
25...¤d3! is even stronger, with a double attack on the queen and rook. White loses material in all lines, for example 26.¥xd5+ ¢h7 27.cxd3 ¦xe1+ 28.¦xe1 ¥xf2−⁠+
26.¤b3 protecting the c2 pawn by opening the second rank, but it would be safer to get the queen out of danger with Qb1. 26...¤xg2 Black again passes up the ...Nd3 tactic. 27.¦xg2µ27...f4 following the precept that passed pawns must be pushed, although this reduces the pressure of Black's pieces. (27...¤f3!?) 28.£c3 ¤c4
28...f3 is favored by the engines and is the logical continuation of the previous move's idea.
29.£f3 White has been doing a good job of containing Black's threats as best she can and the engines show only a slight advantage for Black at this point. 29...£f5³30.¤xc5 White logically wants to eliminate Black's strong bishop, but now the Ba5 is hanging. This is a case of where "doing something" in a position is actually inferior to waiting.
30.g6!? is the engine recommendation, a waiting move that also restricts Black's king. 30...¦ac8 31.£g4 £xg4 32.¦xg4 ¥d6³
30...£xc5 31.b4 £f5µ looking at how the position has transformed, White's bishop is now largely locked away, although may get back into the action via c7. Meanwhile Black's control of the e-file and the well-placed Nc4 are key advantages; the Ra8 can also easily get into the action. 32.¦f2 ¦e4 33.¦g1 ¦ae8 34.¥c7? an apparently logical idea, to increase pressure on the f-pawn and have the bishop do something useful, but now Black's domination of the e-file and her rooks will decide the game.
34.¢h2 would protect the h-pawn, which is vulnerable to pressure along the 3rd rank.
(34.£g4) 34...¦e3!−⁠+35.£xf4 ¦xh3+ a good example of the principle of looking for tactical exchanges, in this case the f-pawn for the h-pawn, since White could not take and also protect at the same time. Obviously the loss of the h-pawn hurts White much more than the f-pawn does Black, due to White's vulnerable king. 36.¢g2 ¤e3+ 37.£xe3 forced. 37...£g4+ here the value of the tactic of gaining a tempo is illustrated, with White's queen moving out of danger. 38.£g3 ¦xg3+ 39.¥xg3 ¦e3 40.¢h2 £h5+ a nice little tactic to pick up the g-pawn and give Black a passed pawn on the kingside. 41.¢g2 £xg5 White does not have compensation for being down material (R+B vs Q). It is instructive to see how Black's Q+R combination holds the initiative and how White is essentially helpless to do anything from this point forward. 42.¢h2 ¦e6 43.¦gg2 £h5+ 44.¢g1 £d1+ 45.¦f1 £d4+ 46.¦ff2 ¦e1+ 47.¢h2 £d1 48.¥f4 £h5+ 49.¢g3 ¦h1 50.¦h2 ¦g1+ 51.¦hg2 ¦h1 52.¦h2 £g6+ 53.¢h3 £e6+ 54.¢g3 ¦e1 55.¦hg2 £g6+ 56.¢h2 £e4 57.¥g5 £xb4 an illustration of the power of the queen to reposition herself with tempo and then pick up additional material in an endgame. 58.¥f4 (58.¥f6?58...£d6+ 59.¢h3 ¦h1+ 60.¢g4 gxf6−⁠+) 58...£e7 59.¢g3 ¦e6 60.¢h3 £d7 61.¢h2 ¦e4 62.¢g3 £f5 63.¦f3 g5 Black is now able to bring another piece into the attack. 64.¥xg5 one last attempt at setting a trap. 64...¦g4+ the tactical intermediate move that finishes things off. (64...£xg5+??65.¢h3)
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