The Long Diagonal Bishop That Eats Rooks Alive

Magnus Carlsen has been carving up rapid fields all month, and if you watch enough of his blitz you notice a recurring flavor of tactic: the fianchettoed bishop that quietly aims at your rook in the corner, waiting for the file or diagonal to open. It looks harmless. Then, three moves later, you're down an exchange for nothing.

Today's puzzle is a pure example of that idea. It's a clearance sacrifice on the long diagonal, and once you see the pattern you'll start hunting for it in your own games.

The Position

Black to move:

FEN: 4k2r/1bqn1pbp/4p1p1/1r1p4/PB6/2P2B2/5PPP/RN1QR1K1 b k - 0 1

Take a moment before reading on. Black has a bishop on g7 staring down the a1-h8 diagonal. What's standing in the way? A single White pawn on c3. And what sits at the very end of that diagonal? The White rook on a1, currently defended by nobody useful.

The whole combination is about removing that c3 pawn with tempo so the g7-bishop can complete its life's work.

The Solution

The move order matters, so let's walk it carefully.

1. 1...Rxb4! — Black's rook on b5 captures the bishop on b4. This is the key. Why give up a rook for a bishop? Because the point is not the material swap — it's what recaptures.
2. 2.cxb4 — White plays the natural recapture with the c3 pawn. But now the c3 square is empty. The a1-h8 diagonal is wide open from g7 all the way to the corner.
3. 2...Bxa1 — The g7-bishop slices down the diagonal and grabs the rook on a1.

Let's count. Black gave up a rook (on b5) and won a bishop (on b4), then won a rook (on a1) with the bishop. Net result: Black wins a full rook for a bishop — a clean exchange up, and White's queenside is in tatters with a knight on b1 that never got to breathe.

Why It Works

The tactic hinges on a single idea: the c3 pawn is the only obstacle between the g7-bishop and the a1-rook. As long as that pawn sits there, the bishop bites on granite. Black's job is simply to force White to move or lose that pawn.

The elegance is that 1...Rxb4 does this with a threat White can't ignore. After 1...Rxb4, if White declines the recapture, Black is just up a bishop for free — so White is essentially forced into 2.cxb4, which is exactly what opens the diagonal. This is called a clearance sacrifice: you sacrifice material specifically to vacate a line for a stronger piece.

Notice too that this only works because the a1-rook is undefended. Always check: at the end of the diagonal, is there a target, and is it hanging? Here the knight on b1 and queen on d1 don't cover a1, so the rook is a free lunch.

Two Supporting Patterns

This same skeleton shows up constantly. A classic is the Boden's-style clearance where a pawn move opens a bishop's line onto a loose piece. And in the King's Indian and Grünfeld, Black's g7-bishop is famous for these diagonal shots — often after a well-timed ...c5 or ...e5 break rips open the center and the bishop suddenly sees the a1-rook or a queen on the long diagonal.

Compare it to a simpler motif: in many Sicilian middlegames Black plays ...Rxc3 to demolish White's structure precisely because a bishop or queen behind it gains a diagonal. Same DNA — sacrifice the exchange on c3, cash in on the newly opened line.

Drill It

Here's how to train this pattern until it's automatic:

• Spot the diagonal. Whenever you have a fianchettoed bishop, trace its diagonal all the way to the enemy back rank. What's there?
• Find the blocker. Identify the single pawn or piece obstructing the line.
• Ask: can I force it to move? A capture with tempo — like 1...Rxb4 — is the ideal tool.
• Confirm the target is loose. No point clearing the diagonal if the piece at the end is defended.

Set up this exact FEN against your engine or a friend and play it out. Then flip the board and look for the same idea from White's side of a King's Indian.

Takeaway

A bishop on the long diagonal is a loaded gun; a pawn in the way is just a safety catch. When you see your fianchettoed bishop pointing at an undefended enemy rook, don't ask 'how do I trade' — ask 'how do I clear the line, with tempo.' 1...Rxb4! 2.cxb4 Bxa1 is the pattern in its purest, most satisfying form.