Zaitsev System

The Zaitsev System leaves the a6-pawn alone and develops with 5. Nc3, inviting Black to recapture on b5. After 5...axb5, by far the most common reply, White can regain the pawn with 6. Nxb5 and stay a pawn up. The more usual plan is 6. e4, using the knight to support the advance, gaining central space and supporting the pawn on d5 rather than spending time on the queenside. Black's main answer, 6...b4, drives the knight away, and 7. Nb5 is the Nescafe Frappe Attack. The knight goes forward instead of retreating, and the e4-pawn is less loose than it looks. After 7...Nxe4 8. Qe2 the knight is pinned against the king, and 8...Nf6 allows 9. Nd6 mate.

Black can also ignore the b5-pawn for now with 5...g6 or 5...d6. These moves continue the usual kingside development and leave the timing of the queenside exchange open. The engine considers the position roughly balanced. In online games Black scores slightly better, especially after 5...axb5.