2025/06/12 DPA: "What A Difference A Square Makes"

Black to move:

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Material is even.

The only loose White piece is the b2 Bishop.

White's f pawn is pinned.  But it's also thrice-defended.

There doesn't appear to be any checkmate threat, as the back rank is well-defended and there are no holes to exploit.

So the puzzle must be about material gain.

Is there some two-move tactic starting with 1. ... Nxc3  2. Bxc3 to lure the Bishop out?

I don't see a LQM/BQM [Lateral Queen Move/Backward Queen Move].

After 1. ... Nxc3  2. Bxc3, what has changed?  Has the Knight move cleared any other pieces to move?  I don't see any.

Is White in Zugzwang?  No.

If 1. ... Qc5 to attack the Knight again, White can simply play 2. Nxd5.

1. ... Nxc3  2. Bxc3 Rc8 [which Rook?]  3. Bb2

Aah, I see it:  1. ... Nxc3  2. Bxc3 Qc7, attacking the Bishop and also threatening 3. ... Qxg3, winning the Knight due to the pin.

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The key for me was noting the pinned f pawn first and then sort of stumbling on how to exploit it second.  This is backwards from what might be perceived as the "correct" way to solve a puzzle but the brain works in myriad ways.

1. ... Nxc3 forces 2. Bxc3 to maintain material equality.

2. ... Qc7 is a dual-purpose move [aka Zombie Attack Scenario, for those who have been reading my blogs for a while] that simultaneously attacks the now-undefended Bishop AND threatens the g3 Knight due to the pin of the f pawn.

It's also a BQM and a quiet one at that.

White cannot save his Bishop with 3. Be5 [moving the Bishop away from c3 and blocking the Black Queen's attack on the Knight] because Black is attacking e5 twice and so will simply win the Bishop.

Nice puzzle by @JohanVA!  I had a suspicion it was one of his due to how difficult it was for a non-weekend puzzle.