piece sacrifice for two pawns and kingside attack - sound or unsound?

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Avatar of AzianPowah
I was white.
Avatar of ArtNJ

I put it into Stockfish for giggles and am shocked that it seems to like the sack.  It doesnt look like you have enough to me -- your pieces are not active, and the pawns are far from menacing in the immediate future.  

This is probably an instructive position to study, if one has the time for that.  

Avatar of cornbeefhashvili

I like the sac. If you can sac with initiative and still outnumber attackers vs defenders in the area, then it is sound. The move 24. Rf4 seems to stick out in my head.

Avatar of AzianPowah

@ArtNJ what line does Stockfish offer as the best defence to my sacrifice? because I was extremely sure during the game and during the post-mortem analysis that Alex just missed a way to refute the knight sac

Avatar of yourChess

All candidate moves mentioned for your 19 move are all good ones and would have been good choices.

However, the move you played in the game is interesting and it is still playable. An improvement for your opponent would have been 21... Ng6 22. f5 Ne5, when the position is unclear. Even after 23. f6 Bf8, it still remains unclear( in my opinion).

With the center relatively closed, I would have immediately discarded( or maybe not even considered) it because after the line aforementioned, I see no move that would end resistance for black. 

Avatar of ArtNJ

Stockfish likes ng6 as the best defense to the sack after running a few minutes on my phone.  At various earlier points, it also liked kf8 or rf8.  It does not like F5.  G4 seems to be white's next move regardless.  And, as mentioned, Stockfish likes white's position a good deal.  

This seems to be very much a slow boil attack, but I suppose the issue is that black is cramped and devoid of counterplay.  

Avatar of AzianPowah

Could anyone provide me with a an alternate plan that doesn't revolve around the knight sacrifice on h5? I was not able to come up with any strategy or obvious plan of attack with the alternate moves 19. Qf3 or 19. h4 and would like to see how the game could have turned out differently.

Avatar of ArtNJ

Qf3 strikes me as more of an "I cant figure out what to do so I'll improve the position of my pieces a tiny bit and try and figure something out later" move.   Qf3, rook over, then what?  Sort of just punting the question of what your plan is.  But sometimes this is the best strategy.  

I dont have any idea what the point of h4 would have been.  What does it do other than weaken your own pawn structure - is h4 or g5 a threat?  Are you going to use h3 to reposition the knight?  Just not feeling it.  

The only human plan thats immediately obvious to me is playing f4, and maybe a well timed f5 after that.  To do that, the knight needs to move somewhere.  Its not obvious to me that this plan actually improves the position, which is probably why Stockfish was looking at qf3.  But its a plan.

Avatar of JGambit

did not look at the position in depth, but I can tell you that from a general perspective that sacing a knight for 2 pawns around the king with queens on the board is often worth considering, esp when you have more space as here.

Avatar of SacrificialChess15

Your sacrifice was completely correct and sound. In fact, it was the best move in the position! Stockfish evaluates the position after 19.Nxh5! as (+1.0). This means you have a serious advantage that is equal to about 1 pawn. By the way, that was a very nice sacrifice!

Avatar of yourChess

One thing that I notice is that your opponent made some innacuracies prior to the sacrifice and that made the knight sacrifice possible. 

On move 5, I would have played something much more conventional, like 5... d6, strengthening the pawn structure and making it less prone for collapse down the road. I can't point my finger in this position and claim that this was the "deciding move," but I can say that it is a peculiar move and I am uncertain about what your opponent was thinking.

On move 6, I would have played 6. Nf3, immediately striking at the center pawns. This prevents 6... h4, which as you mention in your diagram, was missed by your opponent.

Yet again, on move 7, your opponent misses the opportunity to play 7... h4. When this time, it is even stronger because your king is already commited to the kingside. After 7... h4, you don't want to take because that would allow an interesting underdevelopment move, 8... Ng8!?, when the black queen quickly gets into action. Might be interesting to explore. After 7... h4, play could continue 8. d3, when black has his choice when to pry open the kingside. 

I think your opponent would have done better to play 11... a6. At least trying to prevent an upcoming b5. After 11... a6, there should be no rush to immediately play 12. b5, as it gets very messy, but black seems to be the one on top in the end. 12... axb5 13. cxb5 Nd4. Your a-pawn is vulnerable and your opponent's knight would be sitting on a good post. Instead of 12. b5, a better move would be 12. a4, preparing the advance again. With 11... a5, he/she allows the advance and there is no doubt to your advantage since you have a space advantage on the queenside.

I think you could have put more thought into 15. bxc6e.p. because even though it makes the knight on e7 more active, they would have to sacrifice the b7-pawn to do it. However, it is true that after 15... Nxc6 16. Rxb7, they have 16... Nb4, when your rook is very close to get trapped. Instead of 16. Rxb7?!, you have the option between 16. Nf4 going for the knight sacrifice, although it doesn't look as effective because the black queen is there to help out, or 16. f4 preparing f5, when you definitely have the advantage. I'm not saying your move was a mistake, but I am saying that maybe 15.bxc6e.p. needed more attention.

15... Qc8, I think, is a bad move and it is turning his/her position from roughly equal to worse. The immediate threat is obviously Bxh3, but otherwise, this move accomplishes nothing else. I believe it was imperative to keep the queen on d8 and play 15... b6. With the queen remaining on d8, your knight sacrifice idea would always be less likely to work successfully. With your opponent's next few moves, it shows that he/she is completely unaware of a sacrifice occurring.

On move 18, you might have missed the opportunity to play 18. Nxh5!?. However, I think it is at the brink of being unsound.

However, your opponent, on move 18, mostly walks into the sacrifice by 18... Kh7. The difference between the 18. Nxh5 and 19. Nxh5 is that on move 19, you get that essential extra tempo that gives you a safer advantage.

Your opponent made a terrible move on move 21. A better defense is 21... Ng6 or 21... Kf8. I know you mentioned 21... Rf8 as a possible defense, but I don't think it is the best 

24. f4 is good enough, but I think 24. Bh6! is the best continuation. Threatening Bxg7 followed by Rf4. Either way, you get a decisive advantage in both continuations, so it really doesn't matter that much. 

25. Kh1 is playing it safe, but in reality, that minor discovered check that black is threatening is met well by a Bf4. However, at this stage, it doesn't matter. After this, your opponent shows that he/she wasn't prepared for the sacrifice and starts playing horrible move after another.

I hope you like your analysis of your game and if you disagree with any of the above analysis, tell me.