10

The position in question is:

[FEN ""]
[StartPly "13"]

1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. Nc3 e5 5. Ndb5 Bb4 6. Bg5 Bxc3+ 7. bxc3 Qa5 8. Qd5 Nge7 9. Nd6+ Kf8 10. Qxf7# 1-0

It's black turn and the engine is recording to take the hanging bishop, but doesn't Nc7+ fork the King and the Rook? Stockfish is still showing a negative evaluation for this position.

Am I missing something important?

  • 1
    White still won. A fork is only significant if the pressure actually affects the gameplay. – Mast Apr 1 at 12:53
11

White does indeed fork the king & rook after Nc7+ - but after Nxa8, the knight is not escaping, so Black is at worst even on material.

 [FEN ""]

 1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. Nc3 e5 5. Ndb5 Bb4 6. Bg5? Qxg5 7. Nc7+ Kd8 8. Nxa8

After something like ...b6 followed by Bb7, the knight's a goner. White can get at most one pawn for the knight (after Nxb6), which leads to a material imbalance of R+P vs B+N. This particular imbalance is roughly equal, although I've also read that the side with two minors tends to be favored in middlegames since they represent two useful attacking pieces while the extra pawn is only useful in the endgame. Moreover, Black is also way ahead in development (even if he does take some time to round up the knight on a8).

In short, you're not missing anything important insofar as White does not end up grievously behind in material - but Black has more than enough positional compensation.

| improve this answer | |
  • 3
    Black has three moves out of check after 7.Nc7+. If I was playing I guess I'd go Kd8 automatically. My computer at first vacillated between Kf8 and Kd8, but around depth 39 it had a slight preference for Ke7. And after that it lets the white knight in the corner escape, making it an exchange sacrifice after all. I don't understand any of this. Time for me to give up chess and find some easier game. – bof Apr 1 at 8:30
11

I agree with the other two answers, but I feel like I also need to comment on the beginning of the game since there was A LOT more important stuff there than just the answer to why Qxg5.

This is very similar to a Kalashnikov Sicilian by transposition with the exception that the knight is on c3 instead of a pawn on e4, but the ideas are very similar. In particular, the moves Bb4, and Bxc3. The doubled pawns were not worth it, and I will go into why below. There are fairly extensive notes in the game below about the opening play.

 [FEN ""]

 1. d4 (1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 5. Nb5 d6 {This is a normal move order to get to the Kalashnikov Sicilian. Your game is not quite a Kalashnikov, but it is very close, and the strategic similarities are relevant. } (5... a6 {Or this. Ulf's favorite, leading to an endgame.})) 1... c5 2. Nf3 cxd4 3. Nxd4 Nc6 (3... d5 $1 {Take the center!}) 4. Nc3 e5 $2 {This is premature since the N is on c3 instead of e4 having been played. You also have to have a feel for how the hole on d5 needs to be managed. In general, you do not want to create a backwards pawn on an open file.} 5. Ndb5 {Nd5 is now a threat winning on c7.} Bb4 $2 {In similar structures in the Kalashnikov, the bishop never goes to b4, as you almost never want to take on c3. The doubled pawns are not worth it for reasons I will give below, but also because after e5, you have weakened the dark squares around your king. The game actually showed what happened when a knight got to d6.} (5... a6 $1 6. Nd6+ Bxd6 7. Qxd6 Qe7 {Is a main line that Ulf Anderssen plays with the difference being that the N is on c3, instead of e4 being played, so your options were limited to just a6.}) (5... d6 $4 6. Nd5 Qa5+ 7. Bd2 $18 {Is the simplest.} Qxb5 $4 8. Nc7+ Kd8 9. Nxb5) 6. Bg5 Bxc3+ $2 {In many similar positions, the Nc6 will come to d4 with strong threats, but here, giving up the bishop takes that off the table. At least, I would wait until white wastes a tempo with a3, forcing your decision. In addition, a Nd4 gums up any white counterattack down the d-file, and limits white's space.} (6...Qxg5 $19 {This is MUCH stronger here.} 7. Nc7+ Kd8 8. Nxa8 b6 {And black is way ahead in development, and more importantly, it is hard for white to finish development, and catch up.}) 7. bxc3 Qa5 $2 (7... Qxg5 {As you, and the others mentioned.}) 8. Qd5 Nge7 $4 9. Nd6+ {We see the dark squares have the final say due to bxc3 earlier.} Kf8 $2 10. Qxf7#
| improve this answer | |
  • Thanks. That game was very helpful. – AKP2002 Mar 31 at 15:04
  • @AKP2002 You are welcome. – PhishMaster Mar 31 at 15:05
  • 1
    ...what's the point of pointing out 1.e4 (and then showing a random 5-move line) as an alternative to 1.d4? – BlueRaja - Danny Pflughoeft Apr 1 at 1:43
  • 3
    @BlueRaja-DannyPflughoeft To show how closely related the positions are that I referenced in both the main part of my answer, and in the notes. That e4 line is the Kalashnikov, and looks almost the same as the line they transposed into. These ideas for both are very similar. – PhishMaster Apr 1 at 1:46
6

In addition to Allure's comments. Two pieces is favourable to a rook in a position like this where there's no clear squares for the a8-rook to attack, but lot's of squares in the center for the two minor pieces to control.

Black is definitely better after the exchange.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.