11 December 2016

Commentary: 2016 Olympiad Round 7 (Shankland - Sethuraman)

This next commentary game is from round 7 of the 2016 Olympiad in Baku, which saw the United States defeat India 3.5-0.5.  GM Sam Shankland contributed to that by winning the White side of a Slav Defense against S.P. Sethuraman; original ChessBase news and analysis can be found here.  As a Slav player, I found the game interesting; I feel it's important to study losses in your openings, not just wins, which can be common to focus on.

The below game highlights a number of useful chess themes, but it's also a lesson in the value of persistent defense when under pressure, as well as how having the advantage can slip away into a loss.  Shankland was thrown on the defensive after grabbing a pawn and then running out of threats.  However, Black - under time pressure, apparently - missed several follow-up moves that would have more directly converted his advantage, for example around moves 29-30.  Although technically lost (according to the engine), Shankland kept playing effective defensive moves that helped take away Black threats, until the tide turned around move 34.  By the time move 40 was reached, it was White who had the initiative and winning threats, although the win was not assured.  The long queen and minor piece endgame is also instructive to see, both for the principles involved and for the interesting tactic 65...Bg5 which looks like it could have held for Black.

As a final introductory comment, when looking at these types of master games, it's always useful to remember the pitfalls of computer analysis and see why the top engine moves aren't made on the board, which helps improving players both better understand the game and demonstrate how practical choices often need to be made at the board, rather than always striving for an "optimal" move selection.

Shankland, Samuel L (2679) - Sethuraman, S P. (2640)

Result: 1-0
Site: Baku
Date: 2016.09.09
[...] 1.d4 d5 2.c4 c6 3.¤f3 ¤f6 4.e3 ¥g4
4...¥f5 is the other main choice here to stay within the Slav Defense. It's largely a matter of taste which to choose, although this variation offers White an easy route to exchange the Nf3 for the Bf5, if desired.
5.cxd5 cxd5 after the exchange of pawns, Black now has to worry about the e8-a4 diagonal. However, the trade-off for White is reducing the central tension and opening the c-file, which Black usually can find useful. 6.¤c3 e6 White scores a remarkable 68 percent after this move, according to the database. It's remarkable because it doesn't seem warranted with the solidity of Black's position. 7.£a4+ taking advantage of the open diagonal to harass Black. 7...¤bd7
7...¤c6?! lets White pile up the pressure and has not been played in the database. 8.¤e5 ¦c8 9.¥b5 £b6 and now 10. f3!? or 10. b3 look good for White, who can play comfortably on either the kingside or queenside.
8.¤e5 the difference here from the previous variation is that while the knight on d7 is still pinned, it is amply defended. 8...a6 a prophylactic move to take away the b5 square from White's bishop (or knight). 9.f3!? only played once before in the database (a White loss), but Komodo has it near the top of its choices.
9.¤xg4 is a more standard choice, with a knight for bishop exchange. 9...¤xg4 however, this takes the pressure off Black.
9...¥f5 10.g4 the (only) logical follow-up to White's previous move. The kingside space advantage is real, but Black need not panic. However, it requires careful assessment and calculation to select the (only) reply that keeps the balance. 10...¥g6?! this obvious move allows White to benefit from his space advantage and keep pressing.
10...b5 counterattacks immediately, to good effect: 11.£d1 shifting the queen toward the kingside action 11...¤xe5 another counterattack 12.dxe5 ¤xg4 definitely not an obvious move 13.fxg4 £h4+ 14.¢d2 ¥xg4 15.£e1 £g5 and the engine assesses that Black has full compensation in an equal position. It is certainly more fun to play the Black side here.
11.h4±11...b5 still the best idea, but one move too late to preserve Black's game. This is a common phenomenon found in analyzing my own games, as well. 12.£d1 b4 Black must keep up his counterplay on the queenside, as White is much better equipped to play on the kingside. 13.h5 Shankland correctly presses his own plan and ignores Black's threat. 13...¥xh5 with nowhere else to go, the bishop's best move is to kamikaze while the Nc3 remains under threat. (13...bxc3 14.hxg6 ¤xe5 15.dxe5 ¤d7 16.gxh7±) 14.¤xd7 this looks like the easier way for White to proceed, eliminating the idea of ...Nxe5. The engine instead suggests moving the Nc3 out of harm's way first, for example:
14.¤e2 preparing for a kingside transfer 14...¥g6 now Black seems to have gotten away with taking the h-pawn, but... 15.¤xg6 fxg6 forced, due to the pin on the Rh8 16.¤f4 ¢f7 to protect the g6 pawn, again because of the pin 17.e4± and White has more than enough compensation for the sacrificed pawn, with Black's king in an awkward position.
14...¤xd7 15.¦xh5 choosing to have the semi-open h-file and an active rook.
15.¤xd5 would mirror the bishop's kamikaze efforts; Black could then continue with the same tactical motif: 15...¥xg4 16.¤f4 g5 17.fxg4 gxf4 18.£f3 fxe3 19.¥xe3² and Black keeps the extra pawn, but White has compensation with better development and (probably) king safety.
15...bxc3 16.bxc3 £c7 targeting the backward c-pawn. 17.¥d2 although White has the two bishops, this doesn't seem to be an advantage here, as their scope is currently limited. 17...¥d6 18.¥d3 ¤b6 eyeing the c4 square. 19.¢e2 clearing the first rank for White's heavy pieces and getting off the h4-e1 diagonal. 19...h6 this turns out to be rather loosening of Black's kingside and to give White an easy target, although technically speaking it is not a bad move. Other good options: (19...¦b8) (19...g6) 20.g5 Black still has the problem of the pin on the Rh8. 20...¢d7 connecting the rooks and eliminating the pin problem. 21.gxh6 gxh6 Black's h-pawn is now passed, but also a middlegame target. 22.¦b1 ¦ag8 it's always difficult to select from different plausible-looking placements of a rook. Perhaps Black had the intent of provoking White's next move. (22...¦ab8!?) 23.¥xa6? Shankland must have not seen a way for Black's resulting attack to bear fruit here.
23.f4 is preferred by the engine, which would block the Black dark-square bishop and also better prepare the capture on a6.
23...¦g2+−⁠+24.¢d3 (24.¢f1 ¦hg8 25.¦h1) 24...¦a8 switching to offense along the a-file. 25.¥b5+ ¢d8 26.¦xh6 ¦xa2 White remains a pawn up but his king is in an awful position and Black's rooks on the second rank are strongly placed. 27.¦h8+ ¢e7 28.¦e8+ ¢f6 White is now out of threats. 29.¥e1 ¢g7 stopping ideas like Bh4, but
29...¥g3!? would get the Black bishop into the attack and remove a key White defender. This looks like the simplest way to proceed.
30.f4 blocking out the Black bishop. 30...f5
30...¤c4!? would (again) bring another piece into the attack, with strong threats.
31.£b3 Black is still winning here, but has yet to make a knockout move. White meanwhile is doing his best to contain Black's threats and generate some of his own, making winning continuations less obvious to find. The text move for example now makes the e6 pawn vulnerable. (31.¦xe6??31...£c4+ 32.¥xc4 dxc4#) 31...£f7 protecting the e-pawn, but now removing the sacrificial tactic on c4.
31...¦h2 is a subtle continuation, seizing the h-file and setting up the threat of ...Ra3 with a deflection tactic, for example: 32.¦xe6 ¦a3 and now 33.£xa3?? runs into the same mating sacrifice on c4 as in the above variation.
31...¥xf4 is a not-so-subtle way to proceed and win, shattering the pawns around White's king: 32.exf4 £xf4 33.¦e7+ ¢f6−⁠+ with a mate in eight, according to Komodo.
32.£d1 ¤c4 33.¦d8! according to the ChessBase article, Sethuraman only had about two minutes left on his clock at this point, with many complications to resolve. 33...¥e7?! the obvious move, which however gives White a lot of breathing room.
33...¤xe3 is flagged by the engine as best, again with the idea of shattering White's protective pawns, although it is hardly easy to calculate. 34.¢xe3 ¥xf4+ 35.¢xf4 ¦g4+ 36.¢e5 (36.¢f3?36...£h5 with a mating net) 36...£f6+ 37.¢d6 £xd8+ winning
34.¦d7ยต34...¦ab2 this gives White the ability to get back to equality, with the following move.
34...¤b2+ is probably the simplest line, forcing the win of an exchange. 35.¦xb2 ¦axb2 but Black may have been put off by the following line: 36.¥h4 ¥xh4 37.¦xf7+ ¢xf7−⁠+ with a large advantage, but not so easy to evaluate. For example after 38.£h5+ ¢g7 wins handily, as the Bh4 cannot be captured due to the mate on d2. Calculating all this in time trouble would be difficult if not impossible, though.
35.¥xc4 dxc4+ 36.¢xc4 £e8 (36...e5+!?) 37.¦xb2 ¦xb2 38.£a1 ¦b8 again, what looks like an obvious harmless move turns out to be bad for Black. (38...¦e2 39.¢d3 ¦xe3+ 40.¢xe3 £xd7) 39.£a7+⁠− now Black is the one under major pressure. 39...¢f8 40.¢d3 now White's king is no longer exposed to Black counter-threats. 40...¦a8 41.£b7 ¦b8 42.£h1 playing it safe by preventing ...Qh5 and trading off material, leading into an endgame. (42.£c6!?42...£h5 43.¥d2+⁠−) 42...£xd7 43.£h8+ ¢f7 44.£xb8± queen and minor piece endgames are complicated and difficult, but Shankland manages to convert his two-pawn advantage at his leisure. His opponent could not have been in a positive frame of mind for a long, grinding defense. White keeps threatening to exchange queens while removing his king from annoying checks. 44...£c6 45.£b2 £e4+ 46.¢d2 £g2+ 47.¢c1 £f1 48.¢d1 £d3+ 49.£d2 £c4 50.£e2 £a4+ 51.£c2 £c4 52.¢d2 £f1 53.£d3 £h1 54.£e2 £e4 55.£h2 £b7 56.¢e2 £b2+ 57.¥d2 £b5+ 58.¢f2 ¢g6 59.£g2+ ¢f7 60.£f3 ¥h4+ 61.¢g2 £d3 62.£h5+ ¢f8 63.£d1 ¢g7 64.£g1 an interesting tactical trade of material. 64...£xd2+ 65.¢h3+ ¢f8?
65...¥g5 is found by the engine. It is very counter-intuitive, but having the bishop choose to sacrifice itself on g5 appears to make it impossible for White to make progress after Black regains one of the pawns. For example 66.£xg5+ ¢f7 67.£h5+ ¢g7 White has no checks now and must lose either the e- or c-pawn.
66.¢xh4+⁠−66...£xc3 in contrast with the above variation, White now can penetrate the kingside and threaten Black's king. 67.¢h5 £c6 68.¢h6 £f3 69.£g7+ ¢e8 70.£e5 ¢d7 71.¢g7 £g4+ 72.¢f8 £h4 73.£g7+ starting the final sequence. 73...¢d6 74.¢e8 £h5+ 75.£f7 calculating the won K+P endgame for White. 75...¢d5 Black hangs the queen and resigns, although he was lost anyway.
75...£xf7+ 76.¢xf7 ¢d5
76...¢d7 77.d5 an instructive temporary pawn sacrifice in the ending, undermining the f-pawn and allowing the win. 77...exd5 78.¢f6 and wins.
77.¢e7 and the e-pawn is doomed.
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