Nimzowitsch Attack

The Nimzowitsch Attack, 5. Nc3, is White's way of unbalancing the symmetrical Classical Variation. Instead of supporting the center with 5. d4, White offers the knight for exchange. Black nearly always accepts with 5...Nxc3, damaging White's structure. After 6. dxc3 White has doubled c-pawns but open lines for the bishops and queen. A typical scheme is Be3, Qd2 and O-O-O, followed by play against the black king on the kingside. The c-pawns help shield White's king, and White counts on the initiative to outweigh the long-term structural defect. The retreat 5...Nf6 keeps the symmetry and is the main alternative, while 5...d5 is seen less often. Engines rate the position as roughly balanced, and White scores somewhat better in online games.

One trap must be avoided. After 5...Bf5?? 6. Qe2 the knight on e4 is pinned. If 6...Qe7 7. Nd5, the threat to c7 forces 7...Qd7, and 8. d3 then wins a piece. Viswanathan Anand fell into this against Alonso Zapata at Biel in 1988 and resigned after six moves.