D91 Grünfeld Defense: Three Knights Variation, Petrosian System
D91 holds a single named line. It leaves D90 (Grünfeld Defense: Three Knights Variation) with 5.Bg5. White’s pieces and pawns attack seven squares in Black’s half, the fifth-lowest count of the 20 Grünfeld Defense codes. That final move, by the bishop, opens a line for the rook on a1 and the queen on d1 and attacks the knight on f6.
| # | White | Black |
|---|---|---|
| 1 | d4 | Nf6 |
| 2 | c4 | g6 |
| 3 | Nc3 | d5 |
| 4 | Nf3 | Bg7 |
| 5 | Bg5 |
The road to D91
- 1.d4 … 3...d5six earlier stops: A40, A45, A50, D80, E60, E61
- 4.Nf3D90 Three Knights Variation
- 4...Bg7D90 Three Knights Variation
- 5.Bg5D91
The position after 5.Bg5
White has brought out the knight on c3, knight on f3 and bishop on g5; Black the knight on f6 and bishop on g7. Black could capture with dxc4. Undefended and attacked: the pawn on c4. Black is to move and has 33 legal moves.
Closest boards in other codes
| Code | Line | Differs on |
|---|---|---|
| D94 | Grünfeld Defense: Three Knights Variation, Burille Variation | four squares: c1, e2, e3, g5 |
| D96 | Grünfeld Defense: Russian Variation | four squares: c1, d1, b3, g5 |
| D53 | Queen’s Gambit Declined | six squares: g1, f3, e6, g6, e7, g7 |
| D80 | Grünfeld Defense | six squares: c1, g1, f3, g5, g7, f8 |
| D82 | Grünfeld Defense: Brinckmann Attack | six squares: g1, f3, f4, g5, g7, f8 |
| E62 | King’s Indian Defense: Fianchetto Variation, Delayed Fianchetto | six squares: c1, g2, g3, d5, g5, d6 |
| E90 | King’s Indian Defense: Normal Variation, Rare Defenses | six squares: c1, e2, e4, d5, g5, d6 |