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Sheldon M A Wong vs Nir Grinberg
W/EU-ch U20 7677 (1976), Groningen, rd 2
Gruenfeld Defense: Exchange. Modern Exchange Variation (D85)  ·  1-0
ANALYSIS [x]

FEN COPIED

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Kibitzer's Corner
< Earlier Kibitzing  · PAGE 3 OF 3 ·  Later Kibitzing>
Jun-19-08  TrueBlue: <think: <TrueBlue> 22. Bxg6 Kxg6, now what? I guess 23. Qh7+ Kxg5 24. Qg7+ and Qxf8 leaves the game about even... What am I missing?>

<think> 24. Rxd5 and it is game over for black.

Jun-19-08  zb2cr: Thanks <MostlyAverageJoe>. I was not working with an analysis engine; note that in my interchange with <Terry McCracken> I stated that I believed that Black would probably lose a piece.

Given your analysis, and the prevailing opinion, it looks as though the 22. Bxg6 line does in fact end up being stronger than 22. Rxd5. I guess I felt too timid to just sacrifice a piece and was more comfortable with just sacrificing the exchange.

Jun-19-08
Premium Chessgames Member
  johnlspouge: Thursday (Medium): White to play and win.

Material: Down a P. Black has a weak-dark-square complex around Kg8, intensified by the White Pe5 controlling f6 and Qh4 controlling h6. The Nf3 can join Qh4 in attacking h7, and Rd1 attacks Bd5. The Black Qc5 is therefore burdened with defense of Bd5. The only White pieces requiring activation are Be2 and Rf1.

Candidates (20.): Ng5, Rxd5

20.Ng5 (threatening 21.Qxh7#) h5

Other defenses lead directly to mate by the Qh4 at h7 or h8.

21.Bxh5 (threatening 22.Bxg6 or 22.Bg4 then 23.Qh7#)

There is no feasible way to eliminate the threats by refusing the sacrifice, so Black must accept the sacrifice.

21gxh5 22.Qxh5 (threatening 23.Qxh7#)

22Be4 23.Nxe4 (forking Qc5 and Rc3)

White wins an exchange.

I knew I had to be missing a defense (21Kg7) because strengthening the attack with the sacrifice Rxd5 looked so natural.

Jun-19-08
Premium Chessgames Member
  johnlspouge: <<dzechiel> wrote: Well, needless to say, there was a lot more play in this position than I would have suspected. I never looked at 21...Kg7, which is an excellent defensive resource.>

I was just about to write something to this effect, but I beat myself to it :)

Jun-19-08  zooter: <TrueBlue: <think: <TrueBlue> 22. Bxg6 Kxg6, now what? I guess 23. Qh7+ Kxg5 24. Qg7+ and Qxf8 leaves the game about even... What am I missing?>

<think> 24. Rxd5 and it is game over for black.>

How is it game over after 24...Qxd5?

Jun-19-08  eblunt: < zooter: How is it game over after 24...Qxd5? >

24 .. Qxd5 unpins the white f pawn, for 25. f4+ and mate a few moves later.

Jun-19-08  JG27Pyth: Well, some have said first two moves are obvious, but I don't think so... the big question for me was do I start with Rxd5 or Ng5? Ng5 was the obvious move... but I knew Rxd5 was coming, so it was a matter of looking deep enough to figure out how the black queen and bishop would factor into the defense to determine the move order... But I didn't see that black could decline the sac...Kg7, and that with Qxe5 he wriggles out of the mating net.

IMO <this was a _very_ hard puzzle to see all the way to the material gain of 27.Nc3!> 7 moves deep to win a minor piece? Medium? Is it me or is CG trying to give our chess-ego's a major beat-down?

Jun-19-08
Premium Chessgames Member
  lost in space: <eblunt> My impression about 20. Rxd5 was wrong. You and <MAJ> are right, 23...Qd3! makes the difference
Jun-19-08
Premium Chessgames Member
  johnlspouge: <<lost in space> wrote: <eblunt> My impression about 20. Rxd5 was wrong. You and <MAJ> are right, 23...Qd3! makes the difference>

<<JG27Pyth> wrote: [snip] the big question for me was do I start with Rxd5 or Ng5? Ng5 was the obvious move... but I knew Rxd5 was coming, so it was a matter of looking deep enough to figure out how the black queen and bishop would factor into the defense to determine the move order... [snip]>

I very much followed <JG27Pyth>'s logic. Drive 20.Ng5 as far as it would go and retroactively insert Rxd5 if necessary. Early insertion of Rxd5 replaces the Bd5 with Qc5 and is bad, because it gives the Black Q extra defensive mobility, notably access to the square d3, as <lost in space> and others note.

Jun-19-08
Premium Chessgames Member
  YouRang: Like others, I considered 20.Ng5 h5 21.Bxh5! winning a pawn (since 21...gxh5? 22.Qxh5 threatens mate, and to stop it, black has to shed material and accept a defenseless king).

However, I struggled trying to go further if black is wise enough to decline the bishop via 21...Kg7.

I figured it could continue:
22.Bxg6! (winning another pawn) Rh8 (not 22...fxg6 23.Qh7#) 23.Bh5

With this, I've got a nice attack going, I'm up a pawn, black's king is vulnerable. Next, I'll probably play 24.Qg4 (unpinning my bishop and creating a discovered check threat).

Not as good as the game I suppose, but it's sure not bad.

Jun-19-08
Premium Chessgames Member
  Jimfromprovidence: I thought that 22 Rxd5 was a brilliant move, part of a very deep and elegant combination.

Every move is forced. 22.... Qxd5 is necessary or black loses a piece. 23 Bf3 attacks the queen and sets up the mate threat Qh7#, forcing 23...Qxe5. Then, after the three consecutive checking moves, white finishes with 27 Nxc3, below.


click for larger view

What's great about this move is that black cannot take back with 27Qxc3 because of 28 Bd5+!, which wins the queen.

Jun-19-08
Premium Chessgames Member
  johnlspouge: <<Jimfromprovidence> wrote: I thought that 22 Rxd5 was a brilliant move, part of a very deep and elegant combination.>

I agree. Today seems slightly deeper than your average Thursday. Do you have any opinion, <MAJ>?

Jun-19-08  Marco65: <YouRang> 22.Bxg6 Kxg6 23.Qg4 Kh6 is probably nothing more than a draw imho
Jun-19-08
Premium Chessgames Member
  YouRang: <Marco65: <YouRang> 22.Bxg6 Kxg6 23.Qg4 Kh6 is probably nothing more than a draw imho>

I must admit that I didn't see 22...Kxg6. :-(

However, (letting the computer look at it), it seems white wins after 23.Qh7+! Kxg5 24.Rxd5! Qxd5 (white is now down a rook and a knight, but black is facing a king-hunt).

25.f4+ Kg4
26.h3+ Kg3
27.Qg7+ Kh4
28.Qg4#

Funny, eh? :-)

Jun-19-08  jpolchinski: <YouRang> It is amusing that in both lines the key moves is Rxd5!, but for different reasons: in the main line so that Bf3 attacks the queen, in the alternative to remove the Q from the g1 diagonal so that f4 can be played.
Jun-19-08
Premium Chessgames Member
  kevin86: I claim at least half on this one-having answered the first four moves correctly.
Jun-19-08  Kasputin: In terms of material black is up a pawn, but white has some clear attacking chancing against the castled king.

20. Ng5 jumps out as an obvious candidate.

20 ... h5
This looks like the only response. Black has no time to move the f8 rook and try and evacuate the king along the back rank. There's no point commenting on suicidal moves like black taking the f2 pawn with the queen or moving the rook to h3.

At this point I thought briefly about moving the g pawn 2 squares but this looks faster...

21. Bxh5

If black recaptures with the g pawn, then white, after Qxh5, threatens mate again. But this time, black can defend h7 with 22 ... Be4. But that leads to 23. Nxe4. White then regains a B (plus 2 pawns) and forks the black rook and queen. White has a completely won position.

What else can black do instead of 21 ... gxh5?

Well if black moves the f8 rook (e.g., 21 ... Rc8) then...

22. Bxg6 fxg5 [...Kf8 leads to Qh8#]
23. Qh7+ Kf8
24. e6

This move does a couple of things. It prevents the black K from possibly going to d7, and it prevents the black B from arriving at g8 after 25. Qh8. And if 24 ... Bxe6, then 25. Nxe6+ forks the black K and Q.

I am going to back up for a moment here. This line looks winning, but I am a little worried that black, with the disappearence of pawns around the black king, may actually have some sort of defence.

Would it be easier instead of 22. Bxg7 to make a move like...

22. Bf3

This preserve's black's f7 and g6 pawns. It also opens the h file again for the queen. Black cannot move 22 ... Kf8 because of 23. Qh8#. But black might have...

22 ... f6 [or ...f5]

Now comes...

23. Qh7+ Kf8
24. Bxd5

And here black will loose the queen if 24 ... Qxe5 because 25. Rxd5.

From a practical point-of-view I think I will pick 22. Bf3 after 21 ... Rc8. I can see (or at least think I see) that it will win material. Maybe 22. Bxg6 works too. I guess in a real game, I would have to analyze that move when I have a chance to play it.

I should also point out that if black plays 21 ... Rd8, then 22. Bxg6 looks better to me. For instance...

22. Bxg6 fxg6
23. Qh7+ Kf8
24. Qh8+ Bg8
25. Rxd8#

So, to start at the beginning.

20. Ng5 h5 [essentially forced]
21. Bxh5 Rc8 [or ...Rb8, ...Ra8]
22. Bf3 and white should win

Or

21 ... Rd8
22. Bxg6 and white should be rewarded with checkmate.

Black cannot take the bishop on h5 (see above), but does black have anything other than a rook move on 22?

I don't think so. Moving the f pawn on 22 for example allows 23. Bxg6 and I think white wins. Not moving the f8 rook just means that h7 get even more deadly because the black K cannot move to f8. The black K also can't go to g8 either because the white e5 pawn guards f6 - i.e., there is nowhere for the black king to go.

Okay, time to check.

Jun-19-08  Kasputin: Well I missed it. I never really thought about 21 ... Kg7. I did look at Kg7 in an abstract sort of way (i.e., not in any real move sequence) and concluded that the king has nowhere to go from there. But I didn't think about it after 21. Bxh5 - when the bishop, temporarily at least, block's white's queen from the rest of the file. Well I am going to take a break and come back to this and see if I can see what happens/could happen after 21 ... Kg7.

Of course any comments from others on my thinking of possibilities other than 21 ... Kg7 is welcome.

Jun-19-08  Kasputin: <Black cannot take the bishop on h5 (see above), but does black have anything other than a rook move on 22?> oops - I should have said move 21 not move 22
Jun-19-08
Premium Chessgames Member
  patzer2: For today's Friday puzzle solution, White launches an attack on the weakened castled position with 20. Ng5! The immediate follow-up after 20...Kg7 with 21. Rxd5! wins decisive material with the subsequent Knight Fork and Discovered Check threats.
Jun-19-08  PinnedPiece: NOTE TO NEW MEMBERS:

If your mouse creeps upscreen as you click the NEXT > arrow , until suddenly

WHOAH!!!! SIDE FLIP!!!!

Note that you can also use the Left Arrow --> on your keyboard.

Then you won't accidentally click the gameboard frame, which is programmed to perform the aforementioned function.

...

Jun-19-08  PinnedPiece: NOW ABOUT THE PUZZLE:

Surely white does better than 26. Qh3???

Where is my payoff? (I had something else here...not saying my move was better....but check out Qh6 to be followed by Bg4?)

Jun-19-08  spongeworthy: my initial thoughts are -

20. Ng5 ..h5

21. Bxh5 ..gxh5

22. Qxh5

.. and there is no way for black to stop mate by Qh7++

Jun-20-08  Marco65: <YouRang> <Funny, eh? :-)> Yes it is! I learned something: the deeper I look into a position, the more variations I miss...
Jun-20-08  mmmsplay10: <marco65> welcome to the club.
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