Four Pawns Attack, Modern Defense

This line plays 5...Na6 before castling, as an early version of the 6...Na6 system. The knight on the rim heads for c5, where it can press on White's broad pawn front once the center is fixed. White most often answers 6. Nf3. The second choice, 6. e5, gains space against the f6-knight at once and has given White better results. Engines rate White slightly better, and the line is rarely seen.