Anti-Noteboom, Stonewall Variation

This variation arises from the triangle move order 1. d4 d5 2. c4 e6 3. Nc3 c6. White has chosen 4. e3 rather than 4. Nf3, so the Noteboom is off the table. Black then puts the pawn on f5 and does without ...Nf6, reaching a Stonewall formation of c6, d5, e6 and f5 like the one seen in the Dutch Defense. The f5-pawn takes control of e4, and White's 4. e3 has already shut the dark-squared bishop inside its own chain. Black usually aims for a quick attack on the kingside, and a rook lift to f6 is a typical part of it.

5. Nf3 is the usual reply, played in about half of games. 5. cxd5 and 5. Bd3 are the main alternatives. The sharpest option is 5. g4, the Portisch Gambit, which strikes at the f5-pawn at once. It is rarely played, but White scores well with it. The engine also suggests 5. Bd2, 5. Qh5+ and 5. Qc2. It gives White a slight edge, yet in Lichess games Black's results are marginally better than White's.