Some digression:

The new James Bond flick is going to be released soon and I saw a preview still today of a chess game - so I copied it out, looks like this:

http://oi60.tinypic.com/167ms07.jpg

there's a ring on the board at square d7. I don't know what it's about, I guess I'll have to plunk down for a ticket to find out.

Here's the link to the promo still, don't know it it's too long to post here:

What and Where?

But which piece to give up? Not the light-squared bishop because it turns out to be important in a later stage of the attack, enabling the obstructing pawn on f4 to complete its transformation into the free and ferocious pawn on f6.

I think the problem with the bishop sacrfice is that black can just play passively with 33 ♗xe4 ♖f7 and i don't see that white gets anything but the pawn.

Instead 33 ♘xe4 gains a tempo on the queen and with a check the next move, paving the way to sacrifice the dark-squared bishop on c5 in order to play d6 with a double attack:

33 ♘xe4 ♕g7 34 ♘g5+ ♔g8 35 ♗xc5 dxc5 36 d6 ♖a7 37 ♗xa8 ♖xa8 38 ♖xc5 when white's b- and d- pawns look dangerous.

Unfortunately black can sully all that with 35 ... ♖c7, pinning the bishop instead of capturing it.

The pawn on f5 stops 33.f5. This suggests 33.Bxe4 or 33.Nxe4.

In the case of 33.Bxe4:

A) 33... fxe4 34.f5

A.1) 34... Ne5 35.Nxe4 Qf8 (or 35... Qg7) 36.Bxh6 Qxh6 37.Ng5+ Kg7 38.f6+ wins.

A.2) 34... Nf8 35.Nxe4 Rxe4 (35... Qg7 36.Bxh6 as in A.1) 36.Rxe4 + - [R+2P vs B+N] and the threats 37.Bxh6 Qxh6 38.Qf7+ Qg7 39.Rh4# and 37.Rh4 look decisive.

A.3) 34... Nh8 35.Nxe4 Rxe4 36.Rxe4 with the double threat 37.Bxh6 Qxh6 38.Re7+ and 37.Re8 with the idea 38.Bxh6 Qxh6 39.Rxh8+.

A.4) 34... Nh4 35.Rxe4 Nxf5 (35... Rxe4 36.Nxe4 seems to win decisive material) 36.Rxe7+ Qxe7 (36... Nxe7 37.Rxf6 wins) 37.Nxf5 Bxf5 38.Qxh6+ Kg8 39.Rxf5 + - [B+2P].

A.5) 34... Bxf5 35.Qxh6+ Kg8 36.Rxf5 wins a piece at least.

B) 33... Rxe4 34.Rxe4 fxe4 (else drops an exchange and a pawn) 35.Nxe4 looks similar to previous lines.

No doubt the game move "solution 33. Rxe4!," which I missed, is the strongest continuation.

However, it's not clear whether 33. Rxe4! forces a win or simply leads to a lasting but unclear advantage.

GM Keene notes Black can make a fight of it after 33...Bd7! to , and Fritz indicates Black can put up even more resistance with 33...Rg7! to .

Of course the real fun begins after Black's expected 33...fxe4 "show me what you got" reply.

One instructive possibility is if, instead of 35...Rxe4!, Black tries to "save the exchange" with 35...Qg7 (diagram below).

click for larger view

White steam rolls Black with 36. Bxh6 Qxh6 37. Ng5+ Kg7 38. f6+ when play might continue 38...Qxf6 (diagram below)

click for larger view

Here after white 32.Rc4 black played Qf6,moving the queen fromf8. But from f8 the bishop h6 had more protection than from f6.

I guess black had only one desire to chase white queen from "h" file playing Qh4

And now look at the POTD pos.

Black had weakness on h6, weak f5 pawn, black bishop c8 and rook a8 out of the play.

So, my opinion is instead of playing 32...Qf6 was better play 32...Rf7-strategy important square should be overprotected, and at least the rook is more flexible as blocker than the queen.

I don't think that 33.Rxe4 was <surprise> for Krogius, because as good phychologist he remembered how he played as black king's Indian vs Bronstein in 1958, where Bronstein sacr. two rooks for twso minor pieces.

Of course to have such opened long diagonal a1-h8 unprotected is not very nice for black.