Fianchetto Variation, Traditional Line

With 4...Bb7, Black develops the queen's bishop to its natural fianchetto square and meets White's planned Bg2 head-on along the h1-a8 diagonal. This is the Old Main Line, played before 4...Ba6 took over as the modern main line. White almost always continues 5. Bg2, and the engine rates the position as roughly balanced. Black can strike at once with 5...c5, the Sämisch Variation, or develop quietly with 5...Be7 6. O-O O-O. Then 7. Nc3 Ne4 8. Qc2 Nxc3 9. Qxc3 is the classical continuation. White holds more space, but Black's position is sound, and 9...c5, 9...f5 and 9...Be4 are the usual ways to generate counterplay. These lines are known for producing draws, so some players use them deliberately to split the point.

White has several ways to unbalance the game. 6. Nc3 delays castling to prepare the e4 and d5 advances. After 6. O-O O-O, 7. d5 sacrifices a pawn, and White follows with Nh4, either regaining the material or bringing the knight to f5, with good compensation if Black holds on to the pawn. In the main line, 7. Nc3 Ne4 8. Bd2 keeps the knight defended and prepares d5.