Chess Opening Theory/1.Nf3/1…d5/2. g3/2…c5/3. Bg2/3…Nc6/4. d4

Reversed Grünfeld

With 4. d4, white enters the reversed Grunfeld where play can be very sharp. The d-pawn immediately confronts black's centre and forces a response.

Black may respond with 4…cxd4, entering a reversed exchange Grünfeld. However, they may also respond with 4…e6, discovering the f8 bishop's defense of the c4 pawn.