Classical Variation

The Classical Variation, 1. b3 d5, is Black's most direct central reply. The pawn claims space on d5 and opens a diagonal for the c8-bishop. It also discourages White from setting up a conventional center, since an early e4 can be captured and a knight on c3 can be chased by ...d4. It is among the most frequently reached positions in the opening. Engines regard it as level, and in Lichess games White scores slightly better than Black.

2. Bb2 is played in the overwhelming majority of games. The bishop takes the long diagonal at once and, by watching e5, keeps Black from extending the center with ...e5. White's usual scheme is e3 and Nf3 in a flexible order, after which c4, supported by the king's bishop, can challenge the d5-pawn. Compared with the 1. Nf3 d5 2. b3 move order, starting with 1. b3 keeps setups with f4 available. When e3 does not suit the position, White can fianchetto the king's bishop with g3 instead. If White chooses to permit ...e5, play tends to transpose to lines of the Modern Variation.

Black's second move largely decides the structure. After 2. Bb2 c5, White can keep a grip on e5 and aim for a reversed Nimzo-Indian with 3. e3 Nc6 4. Nf3 Nf6 5. Bb5, pinning the c6-knight with an extra tempo compared with the normal colors; this position is also often reached via the 1. Nf3 order. If Black develops in London System fashion with ...Bf5, ...e6 and ...Nf6, White can switch to a double fianchetto and prepare e4 with d3 and Nd2, as in 2. Bb2 Bf5 3. d3 e6 4. Nd2 Nf6 5. g3 Be7 6. Bg2 h6 7. e4 Bh7. That sequence reaches a Hippopotamus-type structure and disturbs Black's otherwise comfortable development.

Alternatives at move two are far less common. 2. Nf3 is the second choice and frequently leads to the same setups with the bishop going to b2 later. 2. e3 is occasionally seen, and 2. Ba3, the Graz Attack, develops the bishop on the other diagonal and is rare. 2. e4 leads to the Scandinavian Defense.