Material: down the Exchange (N+P for R). Backwards P on e6 is weak and blocking in the Light B on d7. N on g4 is hanging. Q and R on f file form a battery. Q threatens mate on h2 defended by Nf3, but White can remove the threat with hxg4. Black K is secure from checks. White Pa2, Bb4, and Ph3 hang. e4 is loose.

Problems to solve:
1. The hanging Ng4.
2. Need to activate the Bd7 and Nc6.
3. Backwards pawn on e6.

Candidates: Nxd4, Nce5, e5, Nge5, Ne3

Black has a LOT of options here and has great counterplay for the exchange sac that happened earlier. How to convert? After a lot of thought and looking at lines (Nxd4, Nce5, e5, Nge5, Ne3), the important points are these:

1. The Ng4 is going to fall, or rather Black will sack a N for this attack. If Ng4 goes immediately (hxg4) then White has defenses. (20.hxg4 Qxg4+ 21.Kh1 Rc6 22.Nh2 creates a bit of a fortress and c3 is secure)

2. The c3 square is all important. And Black can overload there if he can save a N and activate his pieces.

3. The threat on h2# is defensible, and something slow releasing the B to come to h3 is also defensible.

I stared at this for a long time and looked at lots of lines. I couldn't see it and I would probably choose OTB:

19...e5

A. 20.dxe4 Ncxe4 21.hxg4 Nxf3+ 22.Rxf3 Qxf3 23.Qxf3 Rxf3 looks good for Black B. 20.hxg4 Qxg4+ 21.Kh1 (Kh2 invites perpetual?) Qh5+... with threats of Bg4, e4 etc.

Time to check. ... Stunning that this was calculated. Time to read the kibitzing.

<19 Nce5!!>

The tempting 19... Nxd4?? drops a piece without sufficient compensation after 20. Qxd4 Bxb5 21. Qxf4 Rxf4 22. hxg4 Bxf1 23. Kxf1 Kf7 (23... Rxg4? 24. Rc8+ Kf7 25. Ne5+ ) 24. Rc7+ Kf6 25. g5+ Kg6 26. Ke2 Re4+ 27. Kd2 Rb4 28. b3 .

<20. dxe5>

No better for White is 20. hxg4 Qxg4+ 21. Kh2 Nxf3+ 22. Rxf3 (22. Kh1 Qh3#) 22... Rxf3 23. Qxf3 Qxf3 24. Bxd7 Qf7 25. Bb5 (25. Bc8?? Qc7+ ) 25... Qf4+ 26. Kg2 Qg4+ 27. Kh1 Qxd4 28. b3 e5

Even worse for white is 20. Bxd7?? Nxf3+ 21. Kg2 Qh2#.

<20... Bxb5 21. Re1>

If 21. hxg4, White is busted after 21...Qxg4+ 22. Kh2 Bxf1 23. Qxf1 Rxf3 24. Rc8+ Rf8 .

<21... Nxf2!> With this sham sacrifice, Black's idea is to create a decisive pin with mate threats.

<22. Kxf2 d4!> An essential followup and clever deflection that tightens the noose and leaves the Rook with no safe haven.

< 23. Rd3>

Allowing mate-in-one is 23. Ra3?? Qh2#

<23... Qh2+ 24. Kf1 Qg3 0-1>

Hi, <jheiner>. To play the candidate, you "only" need to calculate to

< [snip] 20…Bxb5 (threatening 21…Bxf1)

Black has stabilized the center, with a rock-solid base Pe6. His Ng4 is now immune [snip] >

After that, you know that you have the right candidate: the variation is at worst drawing, even if you just quietly withdraw Ng4.

<19...ce5 20.dxe5 xb5>

click for larger view

We are threatening 20...xf1, not only recovering the exchange, but also potentially displacing the white queen from the defense of the knight. 21.hxg4 is not good enough for white: 21...xg4+ 22.h1 xf1 23.xf1 xf3 24.c8+ f7 25.c7+ g6 26.b1+ h6 27.c1+ h5. (Even though this is the best defense, this is not the deepest line, thus, we do not consider this to be the main line.)

<21.e1>

click for larger view

Now we have to open the f file, so our rook can come to life. The only way to achieve this is the sacrifice (21...xf2!), which white is forced to accept, since both 22...g3+ and 22...xd1 are threatened.

<21...xf2! 22.xf2 d4!>

click for larger view

We threaten mate in one. 23.d3 only delays the mate: 23...h2+ 24.f1 g3 25.e2 xf3+ 26.d2 xd3+ 27.c1 c8+ 28.c2 xc2#. The only other possibility we can see is

<23.e2 xe2 24.xe2 dxc3 25.bxc3 h2+ 26.e3 xh3>

There are two ways to win: A.Simplify all pieces and use our kingside pawns to tie the white king to that flank. B.Use the g pawn to eventually win the white knight.

---

Rybka 3:

At first I thought about Nxd4, but this brings the white queen into play, which I don't like.

Now I am considering putting a knight on e5 - the question is, which one?

Nce5 seems better, because it activates the black bishop, and also after 20. dxe5 Bxb5 the white rook must move from f1 - 21. Re1. But now what is the continuation? I am looking at 21....Nh2. But after 22. Nxh2 Qxf2+ I cannot find the mate.

Maybe I am not on the right track at all.

2) loose or hanging piece: Bd7, Bb5 , Ng5 and h3

3) underdefended pieces: f3 knight was insufficently defended. It was attacked twice and defended twice.

4) partial pin: Bb5 pinned the c6 Knight. But the Knight could still move despite dropping d7 bishop

5) exposed White king: WK missed the protection of g pawn

6) material: Black had N and 1 P for rook

7) out of play piece: f1 rook

candidate: 19 Nce5

a) 20 hxg4 Qxg4+ 21 Kh1 Nxf3 22 Rxf3 Rxf3

b1) 20 dxe5 Bxb5 21 hxg4 Qxg4+ 22 Kh2 Bxf1 23 Qxf1 Rxf3 24 Rxf3 Qxf3 Black is up two pawns plus attacking chance against White king

White material, a Rook for a Knight and pawn.

-0.61 19.h3. a costly move.
Available:-
1. = (0.00): 19.Bxc6 Bxc6[] 20.h3 Bb5 21.Re1 Nxf2 22.Kxf2 Qh2+[] 23.Ke3[] Qf4+ 24.Kf2 Qh2+[] 25.Ke3[] Qf4+ 26.Kf2 Qh2+[] 27.Ke3[] Qf4+ 28.Kf2 Qh2+[] 29.Ke3[] Qf4+ 30.Kf2 Qh2+[] 31.Ke3[] Qf4+ 32.Kf2 Qh2+[] 33.Ke3[] Qf4+ 34.Kf2

2. = (0.00): 19.Qd2 Qd6 20.h3 Nf6 21.Bxc6 Bxc6 22.Rb3 Ne4 23.Qe3 Ng3 24.fxg3 Qxg3+ 25.Kh1[] Qxh3+ 26.Kg1 Qg3+ 27.Kh1[] Qh3+[] 28.Kg1 Qg3+ 29.Kh1[] Qh3+[] 30.Kg1 Qg3+ 31.Kh1[] Qh3+[] 32.Kg1 Qg3+ 33.Kh1[] Qh3+[] 34.Kg1

3. = (0.00): 19.a4 e5 20.Bxc6 bxc6 21.dxe5[] Nxe5 22.Nxe5 Qxe5 23.Qc1 Qd6 24.Re1 d4 25.Rg3 c5 26.Qc4+ Kh8 27.b3 g6 28.a5 a6

4. = (-0.12): 19.Re1 Nf6 20.Bxc6 Bxc6 21.Ne5 Ne4[] 22.Rc2 Nxf2 23.Qd2[] Nh3+ 24.Kg2 Qf5 25.Rc3 Ng5 26.Qe2 Bb5 27.Qe3 Ne4 28.Rc7 Bf1+ 29.Kh1 Bh3 30.Rg1 Kh8 31.Rc2 Bf1

5. = (-0.14): 19.Rb3 Qd6 20.h3 Rxf3 21.hxg4 Rf4 22.Bxc6 Bxc6 23.Qe2 Rxd4 24.Re1 Rf4 25.Qxe6+ Qxe6 26.Rxe6 Kf7 27.Ree3 Rxg4+ 28.Rg3 Rc4 29.Rbc3 g6

White material, a Rook for a Bishop and pawn.

-7.06 21.Re1.
Available:-
1. (-0.61): 21.Qd4 Bxf1 22.Qxf4[] Rxf4 23.Rc8+ Kf7 24.Ng5+ Kg6[] 25.Nxe6[] Re4 26.hxg4 Be2[] 27.Rc7 Bxg4 28.Rxg7+ Kh6 29.Rf7[] Bxe6 30.Rf6+[] Kg5 31.Rxe6 Re2[] 32.Rd6 Rxb2[]

2. (-0.61): 21.Qc1 Bxf1 22.Qxf4[] Rxf4 23.Rc8+ Kf7 24.Ng5+ Kg6[] 25.Nxe6[] Re4 26.hxg4 Be2[] 27.Rc7 Bxg4 28.Rxg7+ Kh6 29.Rf7[] Bxe6 30.Rf6+[] Kg5 31.Rxe6 Re2[] 32.Rd6 Rxb2[]

3. (-0.88): 21.Qd2 Qxd2 22.Nxd2[] Bxf1 23.hxg4[] Be2 24.Rc7 b5 25.Rxa7 Bxg4 26.Rb7 Rf5 27.Rxb5 Rxe5 28.a4 Re2 29.Nf1 Re1 30.Kg2 Be2

4. (-2.09): 21.a3 Bxf1 22.hxg4 Bh3 23.Qd4[] Bxg4 24.Qxf4[] Rxf4 25.Nd2 g5 26.f3 Bh5 27.Kf2 Kg7 28.Rc8 Rf8 29.Rxf8 Kxf8 30.Nb3 Kf7

White material, Rook and Knight for Bishop and two pawns.

-15.75 23.Rd3.
Available:-
1. (-5.71): 23.Rg1 dxc3[]
2. (-6.77): 23.Kg2 dxc3[]
3. (-7.85): 23.Qxd4 Qxd4+[]
4. (-10.23): 23.Ree3 Qh2+
5. (-10.24): 23.Re4 Qh2+

Thanks for the feedback. That's why I show up. Got a lot out of everyone's analysis today. Two points stand out.

1. The simple combination above doesn't serve up an immediate tactical advantage, but rather a positional one. Ironically in my analysis, I identified those three positional weaknesses (backwards e6 pawn, inactive Bd7, hanging Ng4) that needed solutions, but didn't see how effectively Ne5 solved all three in two tempos. But good to see in retrospect that I was on the right track. Getting there.

Black has sacrificed the exchange for a Pawn to reach a complex tactical position: is he right? White has King side weaknesses and hanging pieces. Looking at forcing continuations, 19...Nxd4 looks promising. First variation: 20 Qxd4 Bxb5 21 Rd1 Be2 and White's pieces are hanging. Instead 21 Qxf4 Rxf4 22 h3xg4 Rxg4+ 23 Kh1 Bxf1 24 Nh2 Rh4 and Black has won material. Time to see how the game went.
========
19...Nce5 was played. Ah well.
Playing through the variation, my line is a blunder: 19...Nxd4? 20 Qxd4 Bxb5 21 hxg4! wins a piece <johnlspouge>.

<An Englishman: [snip] My ultimate choice was 19...e5. Anyone know what's wrong with it?> White takes the Ng4 and weathers the storm e.g. 19...e5 20.hxg4 Bxg4 21.Be2 e4 22.Nh2 Bxe2 23.Qxe2 Nxd4 24.Qd1 Nf3+

click for larger view

and now 25.Rxf3! exf3 26.Qxd5+ Kh8 27.Re1 leaves White with N for 2P.

Nature is sometimes kind: things you might dread at a younger age, like being a grandfather, often become joys as you age.

Thanks for the feedback. >

Hi, <jheiner>. I am glad that someone else can make use of my long-winded, solipsistic screeds. You are welcome.

< But good to see in retrospect that I was on the right track. Getting there. >

Black to play (19...?) "Insane"

By jove, I think I've got it! If so, this would have been a perfect week for me if not for my quick rush to judgment on Wednesday, when I tried to make an easy win even easier!

Here, White is up an exchange (rook for knight) for a pawn, but Black has a pretty strong attack brewing (time to finish my coffee) and White has a weakened king position, especially the light squares, f3 and h3; furthermore, if Black could somehow dislodge the knight on f3, he would have mate on h2.

19...Nce5!!

This amazing move (which I found after eliminating other candidate moves like e5 and Nxd4) unleashes the full potential of Black's pieces, uncovering an attack on White's bishop while threatening no less than mate with 20...Nxf3+ and 21...Qh2#. So not really a piece sacrifice per se, as Black comes out ahead tactically. Now, White can rule out 20. Bxd7?? Nxf3+ followed by mate, as well as 20. Nxe5?? Qh2#. He must either play 20. dxe5 or 20. hxg4, but the latter can be quickly dismissed as well.

A) 20. hxg4 Qxg4+ 21. Kh2 (Kh1 is even worse) Nxf3+ 22. Rxf3 Rxf3 and the only way to stop mate is to give up White's queen, i.e. 23. Qxf3 Qxf3 24. Bxd7 Kf7! and Black is way up in material (Q+2P vs R+B), with more pawns to fall starting with the d4 pawn.

B) 20. dxe5 Bxb5 21. Re1

or 21. hxg4 Qxg4+ 22. Kh2 Bxf1 23. Qxf1 Rxf3 24. Rxf3 Qxf3, an easy Q+P endgame where Black queens the d-pawn, or 21. Qd2 Bxf1 22. Qxf4 Rxf4 23. Kxf1 Rxf3! 24. Rxf3 Nh2+, converting to an easy K+P endgame with Black a protected passed pawn ahead.

21...Nxf2!

This move demolishes the remaining defenses, threatening both the queen and Qg3#, so the knight must be accepted.

22. Kxf2 d4! (threatening both dxc3 and Qh2#) 23. Rd3 Qh2+ 24. Kf1 Qg3!, and White is fit to be tied up! White must now resign, or face the likes of 25. Re2 Bxd3 26. Qxd3 Rxf3+, or 25. Ke2 Qxf3+ 26. Kd2 Qxd3+ 27. Kc1 Rc8+ 28. Qc2 Qxc2#.