King's English Variation, Four Knights Variation

With 3...Nc6, Black answers the attack on e5 by guarding the pawn with a developing move. Both sides now have both knights out. White has an extra tempo in this reversed Sicilian setting, but it does not yet commit to a pawn structure. Black's main ideas are the central break ...d5, which frees the queen and the c8-bishop, or ...Bb4 to pin the c3-knight. That pin can be followed by ...e4 or by a capture on c3 that leaves White with doubled pawns. ECO classifies the position as A28, with the fianchetto 4. g3 given its own code, A29.

4. g3, the Fianchetto Line, is White's most common choice, followed by 4. e3 (the Quiet Line) and 4. d3 (the Flexible Line). 4. e4 transposes into the Nimzowitsch Variation of the Four Knights System, and 4. a3, the Korchnoi Line, stops ...Bb4 at once. The rare 4. d4 e4 is called the Bradley Beach Variation. The engine considers the position roughly balanced and prefers e4, e3 and d3. In practice White scores slightly better, and draws are uncommon.