Colle System, Grünfeld Formation

In the Grünfeld Formation, Black answers the Colle with 3...g6 and 4...Bg7, pairing a pawn on d5 with a fianchettoed king's bishop, the same piece arrangement as the Grünfeld Defense but without White's c-pawn on c4. The g7-bishop bears down on the long diagonal toward d4. That gives Black a ready answer to White's planned e3-e4 break, because once the center opens the bishop gains scope. White does without the c3-pawn that usually props up d4 in the Traditional Colle, at least for the moment, and tends to complete development before choosing a plan.

Castling with 5. O-O is the most common continuation, followed by 5. Nbd2 and 5. c3, the last of which scores slightly better for White in practice. The engine also suggests 5. b4, gaining queenside space instead of preparing e4. It assesses the position as level. On Lichess the results are close to even, with Black marginally ahead, and draws are uncommon. Theory is sparse, and the game turns on piece placement and the timing of the central breaks.