If 18...Bxb5 19.Bxb7+ Kxb7 (19...Kd7 20.Qxb5#) 20.Qxb5+ Ka8 (or...Kc8) 21.Qc6#

If 18...Bc6 19.Nxa7+ Kd7 20.Qxe6+ Ke8 21.Qxe7#

If 18...Bd6 19.Bxd6, and same threats.

White castling on move 12. looks ok, he could take initiative with 12...Bd6 instead, threatening mate and then he would have the option to castle either side.

<18.b5! xb5>

Forced, due to the double threat of 19.xa7# and 19.xd4.

<19.xb7+!>

A nice in-between move. Because of the placement of black's very own d8 rook and bishop, the black king cannot escape the danger zone: 19...d7 20.b5#.

<19...xb7 20.xb5+>

<doubledrooks> I always thought a zwischenzug/an intermezzo/ an in-between move/a waiting move were always a time-marking move. This is the first I've noticed where it is a debilitating, crucial check and still remains a time-marking move. Thanks.

<morf> You are a dear! I am concerned when you give the puzzle a cursory before rushing to work. I really hope you find a way of staring at it for at least 5 minutes. If still blank, carry it in your head; it helps. I am resolved on half an hour irrespective of the day of the week. (But to be fair to you, I have time.)

A nice miniature, this contest provides our POTD
for Friday; July 29th, 2011.

1.e4 e6; 2.d4 d5; 3.e5,

The Advance variation ... of the French Defence.

[ More common is the Tarrasch, (3.Nd2); or 3.Nc3 Bb4; 4.e5 c5; 5.a3 Bxc3+; 6.bxc3 Ne7; which leads to the main lines of the Winawer. (See Opening Explorer.) ]

3...c5; 4.c3 Nc6; 5.Nf3 Bd7;

This is one of Black's favored choices today; also played in the top choice of 5...Qb6.

*****

[ For the continuation of: 5...Qb6; 6.Be2 cxd4; 7.cxd4 Nh6; (play) [ See MCO-15, page # 203; beginning with column # 01; and all applicable notes. ]

The main line (from MCO) seems to stem from the following contest: Nunn - Schmittdiel; Dortmund, GER / 1991.
(Nunn vs Schmittdiel, 1991) ]

*****

6.Be2 f6!?;
This leads to many lines (in the center of the board) getting opened early in the game, the tried and true system here is 6...Qb6.

*****

[ According to the "Power-Book" ... Black would do better to play: >/= 6...Nge7; 7.0-0, ² (" ") when White only has a small advantage in this position.

GM J. Timman (2650) - GM M. Gurevich (2643);
[C02] / Bundesliga 99-00 / GER; (R# 4.4) / 1999.
(White won, 1-0 in 36 moves.)

(I did not find the above quoted game in the CG database.) ]

*****

7.0-0 fxe5; 8.Nxe5 Nxe5; 9.dxe5 Qc7; 10.c4,

White sacrifices a button for a little play here.

[ Playable was: 10.Re1, ]

Play (now) assumes a sharp and somewhat forcing nature ...

10...Qxe5; 11.Bh5+ g6; 12.Bf3 0-0-0; 13.Re1 Qd6!?;

This central square looks OK for the Black Queen, although >/= 13...Qf5; also looked like a good candidate move for Black.

There is very little experience in these lines for Black, there are only a handful of games in the CB (on-line) database - from this particular position.

14.Nc3 dxc4?!;

For Black to open more files and diagonals (in this situation) does not seem like a good idea to me. (Fritz - and a few other engines - prefer the play of 14...d5-d4; here for Black.)

15.Qe2 Nf6!?; 16.Qxc4 Be7;

Even though Black is a Pawn up in this position, many of the strong chess engines see a large edge ( ) here for White.

17.Bf4! Qd4?; (Maybe - '??')
Black blunders ... although it was easy to miss White's next move. (Many of our readers did!)

click for larger view

We now have reached the position for today's daily chess puzzle.

[ Best was: >/= 17...Qa6T; ("")
although after an exchange of Queens on a6;
Black's Pawn structure has more holes than
Swiss cheese. ]

Now it is: "White to move and win."
18.Nb5! Bxb5; 19.Bxb7+!, Black resigns. (1-0)

The end would come after:
19...KxB/b7; (Or 19 ...Kd7; 20.QxB/b5#.) 20.QxB/b5+, ...Ka8; 21.Qc6#. (Or 20...Qc8; 21.Qc6#.)