Blackmar-Diemer Gambit Accepted: Pietrowsky Defense

Key ideas for both sides

White

a3 is the engine's choice: it takes b4 from the knight, so Bd3 can come without ...Nb4 trading off White's attacking bishop.
Be3 protects d4 directly; after ...Nb4, Ne5 and Bc4 bring active pieces into play.
Bb5 pins the c6 knight and can double Black's pawns with Bxc6+, then Qd3 aims at h7.

Black

...e6 with ...a6, ...b5 and ...Bb7 is a queenside plan that aims the bishop at the long diagonal.
...Nb4 jumps toward c2 and d3, a strong idea if White skips a3.
...Bg4 pins the f3 knight and adds pressure on d4.

Plans and pawn structure

The knight on c6 makes d4 the target. White's plan is to keep d4 covered with Be3 and play on the kingside with Bd3, short castling and Qe1 or Ne5. Black's plan is ...e6, ...Be7 and castling, or a queenside expansion with ...a6, ...b5 and ...Bb7 aiming toward g2. If White trades on c6 with Bxc6+, Black's pawns are split, but the bishop pair helps.

Where the engine's main line heads: White pawn d4, no e-pawns for White, no d-pawn for Black. White has a pawn on d4 and no e-pawn; Black has no d-pawn. White has more central space; Black's pieces are free and the d4 pawn is a target.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −0.31: a slight edge for Black. Its three top choices for White:

−0.31 6.a3 e6 7.Bd3 a6 8.Be3 b5
−0.49 6.Be3 Nb4 7.Ne5 Bf5 8.Bc4 e6
−0.55 6.Bb5 e6 7.Bg5 Be7 8.Bxc6+ bxc6

Pawns, from White's side.

How it scores on lichess

373 rated lichess games reached this position; White scored 56.0%.

under 120048.5%

1200–159956.2%

1600–199959.6%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

How to play against it

As White, play a3 or Be3 before anything else; the d4 pawn is under fire. An early Bd3 allows ...Nb4 and the trade of your best bishop. If Black plays ...Bg4, break the pin with Be2 or Be3 rather than letting d4 fall.

Questions

What are the moves of the Blackmar-Diemer Gambit Accepted: Pietrowsky Defense?

The Blackmar-Diemer Gambit Accepted: Pietrowsky Defense starts 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Nc6. Its ECO code is D00.

Is the Blackmar-Diemer Gambit Accepted: Pietrowsky Defense good for Black?

Stockfish 17.1 rates the position −0.31 at depth 20, which is a slight edge for Black. In 373 lichess games from our sample, White scored 56.0%. An active and tricky defense for Black; White who knows a3 and Be3 keeps decent attacking chances.

What is the main idea of the Blackmar-Diemer Gambit Accepted: Pietrowsky Defense?

Black develops the knight to c6 to attack d4 and threaten ...Nb4. White must cover d4 and b4 with a3 or Be3 before going for a kingside attack.

What should White play next?

The engine's first choice is a3, with Be3 and Bb5 close behind. 6.a3 stops ...Nb4, so White can develop with Bd3 and Be3 without losing the bishop.

Updated October 2026. Sources and method.