Candidate Moves: xb7+, e7, xd7, xe8+

I spent quite some time on this puzzle - almost five minutes. The lack of forcing moves made me uneasy. I found

24. xb7+ xb7 25. e7 c7

Hi, <zooter>. Nikolai Pilafov wrote the Deluxe Chess Viewer and can be contacted through http://www.geocities.com/pilafovi/C.... Nikolai is pleasant and very open to hearing people's suggestions, although he is rightfully reticent to "improve" his wonderful applet. He probably <would> want to implement underpromotion, so you should contact him directly.

If 21...Nc5, then 22. Rfd2! 0-0 23. Rd4 traps the Black Queen.

If 21...Nxe5, then 22. Qf6! O-O 23. Qxe5 wins a decisive piece with a double attack.

If 21...Bxe4, then White can finish with 22. Nxe4 Qc6 23. Nd6+ Kf8 24. Rxf7+ Kg8 25. Qe7 Qc7 26. Kh1 Qxe5 27. Ne8 Rxe8 28. Qxe8+ Nf8 29. Qxf8#.

Black has some difficulties in trying to stop the passed f-pawn AND keeping his pieces safe. I can exploit this situation by putting my queen in the middle of it. Here is what I found:

24.Bxb7+ Kxb7 <removing a potential defender and drawing the black K away from the defense of his knight> 25.Qe7! <pinning and double attacking the knight, plus it forces the rooks to guard each other (in addition to stopping Pf7)> Qc7 <protecting the knight and unpinning it> 26.Rfd2 <piling on the knight and pinning it against the d8 rook>

click for larger view

If black moves the knight, e.g. 26...Nb6, then 27.Qxc7+ Kxc7 28.Rxd8 Rxf7 (28...Rxd8 29.Rxd8 Kxd8 30.f8=Q)

If black tries to guard the knight with the king, such as 26...Kc8, then it amounts to removal of the guard: 27.Rxd7 Rxd7 28.Rxd7 Qxd7 29.Qxf8+

Once again a puzzle where he have to find the game continuation more or less, as pretty much wins in this position. Nonetheless, I played the most forcing, and thus ingame line, completely till f8=Q.

Current material:
White: 6P, N, B, 2R, Q
Black: 5P, N, B, 2R, Q
+ / -: + P

-ML-
<24.Bxb7†!> seemingly trading off, but White plans a lot more. Rejecting with Kc7 just loses a Bishop, seeing the final position of the acceptance it might be better.

/A\
<24....Kxb7> if Black wants to try something he has to take it. This removes one defender from d8 however, and the second defender is overworked.

<25.Qxd8!> as I've already read above, Qe7, attacking the Knight, wins too, but this is forced. If Black does not capture the Queen he is a Rook down in a worthless position.

<25....Rxd8 26.Rxd7†!> and Black picks up Rook and Knight for the Queen. Now Black can't differ either, as 26....Kc8 27.Rxd8† Kxd8 28.f8=Q just leads to a Rook and Knight down. Black has to recapture.

/B\
<24....Kc7> maybe better as it trades less material.

Yes, a lot of us would probably opt for 17.Kh1 on "positional grounds", not wanting a pinned piece. But, really good players look deeper:

- There were no immediate threats on the rook, nor was the rook responsible for guarding anything, so the pin had little near-term consequences.

- White could probably tell that the pin wouldn't last long anyway. The black Q is easily diverted.

- The rook, although pinned, still threatens f7 (which white employed by playing 19.Qh5, threatening Qxf7+).

- Putting the rook on f2 develops the option for Raf1, doubling his rooks on the open f-file.

- Finally, he might prefer to not tuck his king away in a corner where back-rank vulnerabilites might develop.

More precisely, to promote a pawn on the 7-th rank, right-click and select "Pawn promotes into >" and select your choice from the submenu.