I think white's fine until this blunder. 25.Nf3 is a better way to defend d4 and it's not clear that black would have sufficient compensation for his exchange sac since white has as many attacking chances.

<Penguincw: I had 25...Qc1 is mind. It's probably winning as well...>

After examining material balance, I examine King safety, which determines the continuation here.

The White Kg1 has two squares g1 and h1 available to it, which suggests the back-rank mate. White can play 26.Qe5-e6+ or 26.Qxg7#, so a combination requires forceful play by Black. Thus, the only check 25...Qe3+ is interesting.

But it's not quite so simple. What happens if White wriggles like a good un? After 25...Qe3+ 26. Kh1 Qxe1+ 27. Rg1 Nf2+ 28. Kg2, we get to here:

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In human mode I spent quite a bit of time pondering this position. No immediate mate is apparent, so what do we do? We ought to notice that we even though we snaffled a rook in the combination, we are not a rook ahead. We started the puzzle the exchange down, so winning a rook really means winning a minor piece. We've won material but not cornered the blighter yet.

Being a pragmatic soul, I thought of exchanging down to a win on wood. 28...Qxe5 29. dxe5, then extricate the even more deeply infiltrated paratrooper knight, neutralise white's passer and grind out a 60 move win.

And I have to admit that said variation taxed what remains of my grey cells as I worried that the knight might be cornered and lost or the white pawn would race through to Westminster Abbey.

But m'learned colleagues <agb2002> and <gofer> have spotted the better continuation. After 28...Qxd2!

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Black threatens a devastating discovered check and white doesn't have a perp or mating attack of his own. Fritzie subsequently says that this is mate in 11, where my grubby queen swap is in the ball park of -6.

A quick look at this game.

1.d4 d5; 2.Nf3 e6; 3.e3 Nf6; 4.Bd3 Bd6; 5.0-0 0-0;

So far, White is playing the super-safe Colle Opening. [ See MCO-15, page # 506.]

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Meanwhile ... Black adopts the "copy-cat approach."
(I also have had trouble with coming up with an effective plan when my opponent simply mimicked all of my moves.)

6.b3 b6; 7.Bb2 Bb7; 8.Nbd2 Nbd7;

So far, so good.
(Total symmetry, which is somewhat rare in master-level chess today.)

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Both Fritz and Houdini rate the current position as about equal, and it is difficult to even try to dispute such a logical assessment.

Now White buries a Knight into the outpost on e5.

9.Ne5 c5; (Hmmm.)

Black breaks on the Q-side.

Since I first began studying chess, I know that such a break is both correct, normal and good chess.

[RR 9...Ne4; - Fritz 13. ]

10.f4 Rc8; 11.Qf3! Qc7;

Both side have developed in a relatively logical manner, now the players need to decide on a course of action for the middlegame.

12.Nxd7!?, (Illogical?)

White swaps off the monster Knight on the key e5-square.

To me, this is not the best way to handle this position. What is funny is that even the engines do not show a simple or easy path for White ...

[ The iron giant likes: RR 12.Qe2!? Ne4; 13.Nxe4 dxe4; 14.Bb5 Nxe5; 15.fxe5 Be7; 16.c4, (more space) with <maybe> a small edge for White. ]

Now White's P.O.D. is revealed, Maroczy is hoping to make inroads on the King-side.

12...Nxd7; 13.Qh3 f5;

White has done all that he could (thus far) and reaches a (temp?) stopping point.

14.g4!?, (Dubious?)

White lashes out ...

This is probably too violent and compromises White's King-side too much to be one-hundred percent correct.

[ 14.Nf3 h6; ∞ (unclr) ]

14...cxd4; 15.Bxd4 e5?!;

Black goes for a "break-loose" type of idea. (Looks OK?)

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Ferocious Fritz brands this as just plain bad ...

16.fxe5 Bxe5; 17.Bxf5 Rxf5!;

Out of either desperation or a good sense of self-defense, Black sacks the exchange and the box verifies this as the correct approach for Beihoff.

[ Much worse was: </= 17...g6?; 18.Be6+ Kg7; 19.g5, & White's winning. ]

Amazingly, the next three moves are all 100% best, according to the computer. (Who says all old chess is bad chess?)

18.gxf5 Bxd4; 19.exd4 Qxc2; 20.Qe3 Nf6!; (Head for the OP?)

Black goes for the e4-point.

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Fritz indicates that White should be winning here ... (It's not that easy to play Maroczy's position, Black has a lot of counterplay and the WK is not at all secure.)

***** ***** ***** ***** ***** ***** ******

Now both Houdini & Fritz show that Rac1 was best for White. (Maroczy might have seen this, but backed away ... Black could sack on c1, and the WK will have a hard time finding a safe haven on the chessboard.)

21.Qf4!? Ba6!; 22.Rf2!? h6; 23.Re1 Qc3;

Black has done the best that he could do, Fritz reveals that 24.Re7! was just a won game for White.

24.Rg2 Ne4; 25.Qe5??,

White drops the ball ... just inches from the goal-line!

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Now we have reached the position for today's POTD.

[ Better was: ¹25.Kh1, with a won game for White! ]

Black to move and win: 25...Qe3+!; (Ouch!!!!)

Beihoff apparently does not miss his opportunity!

Maroczy shoots up the flag of surrender, there was no point in continuing from here.

It is easy to see that if black delays the attack he can be mated on g7. On the other ahnd, he has a superb Bishop on a6 that can bring him win (with the help of other pieces of course):

25...........Qe3+
26.Rxe3 Rc1+
27.Nf1 Rxf1#
<27.Re1 Rxe1+ 28.Nf1 Rxf1# could be another line to delay mate>

If Queen is not taken, an interesting line is created:

I have ruined the score (taken the easy way out) of some darn nice games to lock down the full point. Beautiful wins are great, but losing on time while looking for beauty is unacceptable.

Nobody touch white queen on f4.

If White takes, then it's mate in 3.

drew Kupchik, who played an Exchange Slav: Kupchik vs Maroczy, 1926.

drew Kashdan: Kashdan vs Maroczy, 1926.

beat Norwood: Maroczy vs C E Norwood, 1926.

beat Cohen: Maroczy vs S Cohen, 1926.

beat Herman Steiner, who went on to become a strong player but was only about 21 at the time: H Steiner vs Maroczy, 1926.