Blumenfeld Countergambit

The Blumenfeld Countergambit, often called the Blumenfeld Gambit, belongs to the Benoni family and is classified under ECO E10. The order given here typically appears when White plays 3. Nf3 to sidestep the Nimzo-Indian; it can also come from 1. d4 Nf6 2. c4 c5 3. d5 e6 4. Nf3 b5. With 4...b5 Black strikes at the c4-pawn that supports d5, offering a flank pawn for the chance to remove White's d5-pawn and set up pawns on c5, d5 and e6. Its name honors the Russian master Benjamin Blumenfeld, and Alexander Alekhine took it up in later years.

When Black obtains the intended center, the light-squared bishop goes to b7 and the dark-squared bishop to d6, and a rook uses the half-open f-file; the attacking chances lie on the kingside. White, for his part, aims to break the center with e4 and can use the extra queenside pawn to generate play on that wing. The engine gives White a slight edge, and White scores somewhat better in the database.

In the Lichess games, 5. dxe6 is the most frequent answer. After 5...fxe6 6. cxb5 d5 (the Blumenfeld Countergambit Accepted) White keeps the pawn while Black controls the center; the usual seventh moves are 7. Nc3, 7. g3 and 7. e3. Black can instead play 6...a6, when 7. bxa6 Bxa6 opens lines on the queenside, although White frequently declines the offer with 7. e3. Grabbing immediately with 5. cxb5 has produced good results for Black.

The Duz-Khotimirsky Variation, 5. Bg5, pins the knight that guards d5 and has scored well for White. After 5...exd5 6. cxd5 Black may play 6...h6, the Spielmann Variation, typically met by 7. Bxf6 Qxf6 8. Qc2, or 6...d6, after which 7. e4 a6 8. a4 Be7 is a standard sequence. A different approach is 5...b4, gaining space on the queenside, with 6. e4 d6 as the normal follow-up.

Among rarer fifth moves, 5. e4 was chosen by Akiba Rubinstein, and 5. a4 occurred in Rubinstein–Spielmann, 1922. The same ...b5 thrust is found in the Benko Gambit, which can transpose here if White answers 3...b5 with 4. Nf3 and Black follows up with 4...e6, though 4. Nf3 is not White's usual choice in that position.