<Shams: maybe something like 20...f6 21.Nh6+ Kh7 (...Kxg7 22.Nf5+ wins the missus) 22.Be4+ f5 23.Bxf5+ Kxg7 24.Rxe6 d8 25.Ng4!>

Instead of 22...f5, though, Black can simply play 22...Kxg7 (23.Bxd5 Qd7 24.Ng4 Qxd5 25.Qh6+ Kg8 26.Nxf6+ Rxf6 27.Rxc8+ Bxc8 28.Qxf6 Bb7 29.Qxe6+ Qxe6 30.Rxe6 is better for White, but not so clearly winning); so White should play 22.Nf5! It should also be pointed out that 21...Kxg7 22.Nf5+ exf5 23.Rxe7+ Nxe7 24.Bxb7 gains another pieces as well as the queen, otherwise it wouldn't be enough for a clear winning advantage to White.

And in case of 20...f6 21.Bxf8 Qxf8, White also has a clear win with 22.Bxd5, e.g. 22...exd5 23.Rxc8 Bxc8 24.Re8!

<<AlfieNoakes>: Yay! Got this, and pretty quickly too :)>

I sometimes get frustrated when I see people putting posts claiming that they solved the puzzle but provide no evidence of a line or anything.

Whereas others like <zooter>, <dzechiel>, and myself included go through the trouble of analysing etc to benefit ourselves and hopefuly others

I had quite a few lines for this, neither one was the 100% correct one, although I did get the first couple moves right

The first move that stuck out to me was 20. Nh6+!
I wasnt to stressed over 20... gxh6 since 21. Qxh6 is very threatening against black and gives black no waiting moves e.g. hxg4 Rxc4

Anyways here are the lines I saw, tell me what you think

/A\
20. Nh6+! gxh6
21. Qxh6 f6
22. Rh4 Qh7
23. Qg5+ Qg6
24. Qxh5
Unclear...

/B\
20. Nh6+! Kh8
21. Rh4 Nf6?
Unclear...

/C\
20. Nh6+! Kh7!?
21. Be4+ g6
Unclear...

/D\
20. Bxg7! Kxg7
21. Qh6+ Kg8
22. Qxh5 Nf6?
23. Qg5+! Kh8
24. Nxf6 Bxg2
Unclear...

/E\
20. Bxg7+! Kxg7
21. Qh6+ Kg8
22. Re5! f6?
23. Rxh5 Qg7(almost forced)
24. Nxf6! (aiming for Rg5 pin)
Unclear...

I think move order is important here to, since both black and white have pieces en prise.

More importantly though...

How did black get into a losing position before whites 20th move?

A) 20.Nh6+

A.1) 20... Kh8 21.Nf5 threatening Nxe7 and Qh6+.

A.2) 20... Kh7 21.Rh4 g6 (21... gxh6 22.Rxh5 followed by Qxh6+) 22.Ng4 g5 23.Rxh5+ Kg6 24.Rh6+ Kf5 25.Qd3+ Kxg4 26.Qf3 mate.

A.3) 20... gxh6 21.Qxh6 f6 (21... e5 22.Rxe5) 22.Qxh5 (22.Rxe6 Qxe6 23.Qg6+ Kh8 24.Qxh5+ Kg7 25.Rg4+ Qxg4 26.Qxg4+ Kh6) Rxc4 (22... f5 23.Qg6+; 22... Rfd8 23.Rg4+) 23.bxc4 recovering the piece with advantage.

Another possibility is

B) 20.Bxg7

B.1) 20... Kxg7 21.Qh6+ Kg8 22.Bxd5 f5 (22... hxg4 23.Rxg4+) 23.Bxe6+ Rf7 24.Nf6+ winning.

B.2) 20... hxg4 21.Rxg4 f5 22.Bxf8+ Kxf8 23.Qh6+ Ke8 24.Rg8+ and Rg7 winning the queen.

B.3) 20... Rxc4 21.Bf6 Nxf6 (21... Rxg4 22.Bxe7 Nxe7 23.Bxb7) 22.Qg5+ Kh8 23.Nxf6 winning.

I think I’d go for 20.Bxg7. Time to post and check.

The last time I said something similar, there was a little war of words which lasted the whole day! Nevertheless, I know exactly how you feel. Good to know I'm not the only human here solving these puzzles.

20. Rxc8 Rxc8
21. Bxd5 Bxd5
22. Qxd5! exd5
23. Rxe7 hxg4
24. Rxa7 Nc5
25. b4 Nd3
26. Bd4 b5

20.Nh6+ seemed questionable after looking at a few variations. 20...gxh6 21.Qxh6 f6 and already black seems to be getting a defendable position with the black queen possibly coming over to g7 or h6. So I stopped looking at Nh6+ to look at better possibilities.

20.Qh6 is a very strong threat but after 20...gxh6 21.Nxh6+ Kh7 22.Be4+ Kxh6 and black wins.

20.Bxd5 looks very good since it removes a potential kingside defender for one thing.

* 20...Bxd5 21.Qxd5 exd5 22.Rxe7 dxc4

* 20...Bxd5 21.Nf6+ gxf6 22.Qh6 e5 23.Rh4 is looking very dangerous for black.

* 20...Bxd5 21.Nf6+ Kh8 22.Nxd5

20.Bxg7 looks "standard" for these types of positions. The key is to destroy the defensive pawn shield to subject the king to a flash attack.

* 20...Kxg7 21.Qh6+ Kg8 22.Bxd5 Bxd5 23.Nf6+ Qxf6 24.Qxf6 and I stopped analyzing because I thought white was just winning.

* 20...hxg4 21.Rxg4 threatens a discovered check and the loss of the queen or mate. (21.Qh6? f6 creates an escape square for the king)

a> 20.Bxd5 Bxd5 Now 21 Bxg7
If 21..Kxg7 then 22.Qh6+ wins for white. Black's queen is lost after 22..Kg8 23.Nf6+ If Black doesnt want take the Bishop. The alternatives look even worse

21..hxg4? Allows Rxg4 after Qh6 mate is almost not preventable without the loss of Queen.

21..Kh7? then Qh6

21..Any moves by Rook on f8 allows Qh6 as well.

b> 20.Nh6+ I think this is less forcing but still wins. For Instance 20..gxh6 then after 21.BxN BxB I think 22.Qc3 is winning 22..f6 allows RxR winning an exchange.

c> I think we can also start with Bxg7. 20..Kxg7 21.Qh6 Kg8 22 BxN BxB 23 Nf6 winning

18…<Bxd5> 19 Bxd5 20 Ng4 Qd8.

click for larger view

But as soon as you consider 20.Bxg7, the rest falls into place pretty quickly:

The king recaptures, 20...Kxg7 and we bring our Q into the attack with check, 21.Qh6+ Kg8 (forced).

Interesting point, but there's a flip side. I try not to repeat things that others have said. What would be the point of seeing twenty or so posts all just trotting out the same line? Especially if it was also the line played in the game?

So I will usually restrict my posts to something that is new and has not been said before. This could be an alternative winning line or (more often, regrettably) a mistaken line that I blundered into.

I don't see this as a competition where any of us have to prove that we solved a particular puzzle. I am more interested in what we can learn.

So if folk want to post along the lines of "Yeah, dead easy, solved it in a nanosecond", that's fine by me. I treat posts like that the same way that I treat emails offering to sell me cheap watches or enhance my bedroom abilities. A little smile and then pass on to the important stuff.

But I will carefully read posts from the likes of Dzechiel, YouRang, LostinSpace and the other regulars because I have a hell of a lot to learn from them.

Please, let's not get into a situation where we feel we have to prove whether we solved it or not. If someone wants to pretend they solved a puzzle, they could get around that by copying out the game score or loading up Fritz, Rybka, etc.

If you've solved a puzzle, it really doesn't matter to anyone else except yourself.

In my defense I believe there is at least one other good try, beginning 20.Rxc8 where practically speaking black can get into some difficulties.

e.g. 20.Rxc8,Rxc8 (..Bxc8 21. Nh6 +, gxh6 22. Qxh6, f6 23. Bxd5 )21.Bxd5,Bxd5 (..hxg4? 22. Qd4! and 22.Bxb7,Qxb7 23.Qg5 ) 22.Bxg7, hxg4 (22.Qxd5,hxg4 -/=) 23. Qh6,f5 24. Qh8+,Kf7 25.Qxc8,Kxg7 26.Qxa6

These were the lines I went for, but the game continuation is obviously much better. At least no chance of white losing in my lines :-)

<DoubleCheck How did black get into a losing position before whites 20th move?

Answer: Most likely with that questionable 19...h5??
The position after 18...Nxd5 is a small space/development advantage for white but nothing overly significant until 19...h5?? was played>

I disagree.

7. ... Be7 is tame, but playable. I prefer Bd6 since it attacks the center and forces White to commit to defending the e5/c5 squares. At this point, neither of Black's bishops are on terribly good squares, but, in Black's defense, it is only the seventh move.

White responds with the aggressive 8. Ne5 (Qc2 is also playable and could transpose with Ne5). Black plays 8. ... 0-0 in response. Normally I'm not one to criticize a safety first mentality, but already White is building a dangerous center. I think the need to counter in the center outweighs castling at this point so, I would have played 8. ... Nfd7.

10. ... Na6? An odd, if unnatural move by Black that has the knight either going to c5 (most likely), c7 (to protect d5, but way too slow given the position) or even b4, but misses the point. White wants to control d5, preferably by occupying it. Nbd7 is stronger, especially in conjunction with Bd6.

As when Black played Be7, White responded aggressively with Ne5, here again, White responds aggressively to 10. .. Na6 with 11. e4!? Given that Black's queen side knight is out of position, this move makes sense. White recognized that Black was making positional moves and sought to bring direct pressure in the center before Black was ready. Other moves were the quieter a3, Rc1 or even e3.

Black ignores the the threat to the center and plays 11. ... Rc8 which is thematically consistent with his other moves up to this point. Black doesn't have really any better options. Bb4, Qc7, Re8 or even dxc4 were all possibilities.

12. Re1 is fine in the face of the impending Bb4. Also playable was Qe2 followed by f3, but I like the game move better since it doesn't weaken White's king side at all or hinder the bishop on g2.

Black plays 12. ... Bb4 seeking get rid of his bad bishop and to weaken the c4 pawn. Since White has the knight on e5, it doesn't worry White in the least, but Black has nothing better.

13. exd5 cxd5 14. a3 Bxd2 15. Qxd2 is a natural progression. 15. ... Qc7 16. Rac1 dxc4 17. Rxc4 Qe7 is not as accurate as 15. ... Qe7 16. Rac1 dxc4 17. Rxc4 which leaves Black with the initiative. Its a small error, but combined with previous moves (e.g. Na6), it adds up. With Black's dark squared bishop off the board, f3 is an alternative to Rac1. However, I like the game move better for reasons given above.

Up to this point, if you were using a computer, it would probably tell you that the position has been and still is essentially even or slightly in White's favor. However, all of White's minor and major pieces are active. His central pawn can advance, and thanks to Black's inaccurate play, he still possesses the initiative to advance it. Moreover, Black's queen is unprotected and indirectly threatened by the White's rook on the half open e-file.

18. d5! shatters Black's position. Black really has no good reply. Sooner or later, Black will either recapture with the e6 pawn losing his queen or have to recapture with the queen on f6 losing it in the process. I suppose Black chose 18. ... Nxd5 to avoid dropping his queen to the rook, or maybe he thought that he might have enough material to compensate for losing the queen on f6. Or maybe, he just overlooked 19. Ng4! In any case, no matter what Black does, White has a winning game though he still needed to play accurately to win.

19. ... h5 was maybe not the best. f5 might have put up more resistance in that he would not have been mated.

Certainity is <unnatural> since the bishop is on a6

The position after
9... Bb7 is fine with the obvious Bb2 and Nbd7 to come