5. Petrosian System with 7.d5 a5 (Iron Grip)
Tigran Petrosian closed the center with 7.d5 and then pinned the f6 Knight with 8.Bg5. Black responds with ...a5 to stop b4, maneuvers the Knight to a6, and unpins the Queen with ...Qe8, preparing the ...f5 advance.
1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.d5 a5 8.Bg5 h6 9.Bh4 Na6 10.Nd2 Qe8 11.O-O Nh7 12.a3 Bd7
Move by move
- 1.d4 – White occupies the center with the Queen's pawn: it controls e5 and c5 and paves the way for the c1 Bishop and the Queen.
- 1...Nf6 – Black develops the Knight and controls e4 and d5: it prevents an immediate 2.e4 and prepares the King's Indian setup.
- 2.c4 – White gains central space with the c-pawn: it controls d5 and prepares Knight development to c3.
- 2...g6 – The signature move of the King's Indian: Black prepares the fianchetto of the Bishop on g7 to target the center from afar.
- 3.Nc3 – White develops the Knight toward the center: it protects d5 and prepares full central conquest with e2-e4.
- 3...Bg7 – The Bishop takes position on the long h8-a1 diagonal: it controls the central d4 and e5 light squares and shields the King.
- 4.e4 – White sets up the classical center with the d4 and e4 pawns: it controls plenty of space but provides a clear target for Black's counterplay.
- 4...d6 – Black restrains White's e4-e5 advance, protects the central dark squares, and prepares the thematic ...e5 counter-strike.
- 5.Nf3 – Classical development of the King's Knight: it controls d4 and e5 and prepares rapid kingside castling.
- 5...O-O – Black secures the King with kingside castling before opening the center; the f8 Rook will support the future ...f5 push.
- 6.Be2 – White develops the Bishop to e2 in solid and positional fashion, preparing kingside castling without obstructing other pieces.
- 6...e5 – The thematic central breakthrough of the King's Indian: Black directly attacks the d4 pawn and challenges White's territorial dominance.
- 7.d5 – White closes the center without castling, intending a positional setup centered on the Bg5 pin.
- 7...a5 – Classical prophylaxis: Black stops the b2-b4 push and secures the c5 foothold for the Knight.
- 8.Bg5 – The hallmark of the Petrosian System: pinning the f6 Knight to discourage or delay the ...f5 break.
- 8...h6 – Black questions White's Bishop immediately, gaining space on the kingside.
- 9.Bh4 – The Bishop retreats to h4 to keep the pin active along the h4-d8 diagonal.
- 9...Na6 – Development toward the ideal outpost: the Knight heads for c5, where it will be untouchable and control e4 and b3.
- 10.Nd2 – White relocates the Knight to prevent jumps to e4 and prepare a3 followed by b4 to contest the queenside.
- 10...Qe8 – Key move: the Queen unpins itself from the h4 Bishop and positions to support the ...f5 break.
- 11.O-O – White completes kingside castling, securing the King before initiating operations on the queenside.
- 11...Nh7 – The Knight moves to h7 to clear the path for the f-pawn and prepare bishop trades via ...Bg5.
- 12.a3 – White prepares b2-b4 to dislodge the Black Knight once it reaches c5 and open the a-file.
- 12...Bd7 – The light-squared Bishop develops to d7, continuing to hinder White's easy b4 push.
How to exploit the position
A closed and strategic position: Black has unpinned the Queen with ...Qe8, restrained White's queenside expansion with ...a5 and ...Bd7, and prepared the thematic ...f5 break.
- Play ...f5 to open the f-file and put pressure on the White center.
- If White pushes b4, exchange with ...axb4 and after axb4 infiltrate with the Knight via ...Nxb4 winning a pawn.
- Maneuver the a6 Knight to c5, where it occupies a magnificent outpost controlling e4 and b3.
- Bring the g7 Bishop to h6 to trade White's light-squared defender and increase pressure on f4.
Master tips
Unpinning with Qe8 in the Petrosian System
The Bishop on h4 looks annoying, but ...Qe8 neutralizes it, connects the Rooks, and supports the ...f5 break.