Indian Defence Deep Lines: KID, Petrosian 8.Bg5
The Bg5 pin: the Petrosian system's main line pressure.
Indian Defence Deep Lines: KID, Petrosian 8.Bg5 is one of the most compelling entries in the Encyclopaedia of Chess Openings — and a line that repays every hour you sink into it.
After 8.Bg5 the position resolves into a tense centre: the central pawns still face each other, and the timing and manner of the coming exchange shapes the whole middlegame.
This is a branch of the Indian Defence Deep Lines. If you are new to the system, start with the parent guide and return here when you want to go one move deeper.
The moves
After 8. Bg5 — Indian Defence Deep Lines: KID, Petrosian 8.Bg5 main line
Position breakdown
A factual read of the position after the main line — the files, the centre, the pawn structure and king safety that decide how the middlegame is played. These are computed from the actual board, not generic advice.
Files
Centre control
Tense centre
The d4/d5/e4/e5 squares — who occupies the centre decides how open the game becomes.
Pawn skeleton
Pawns only — the structure that explains every open file and majority at a glance.
Material level
Queenside pawns 3–3
Kingside pawns 3–3
Development
2 knights, dark-squared bishop & light-squared bishop active
2 knights & dark-squared bishop active
King safety
White king e1
Uncastled — take care
Black king g8
Castled kingside
Computed from the final position of the main line above — 15 plies, black to move.
Strategic ideas
Ideas for White
Master the move-order subtleties: these lines transpose or diverge by a single tempo, and knowing which is which is preparation itself.
Ideas for Black
Pick one defence per main system and drill it deep — Indian defences reward structure-masters over tacticians.
Plans & pawn structures
- 1The central tension is the key decision: releasing it too early hands the opponent a free tempo and a target, so keep it until a capture wins a file, a diagonal or a clear structural edge.
- 2Trade correctly: before every exchange ask which piece benefits from the resulting square colours and pawn structure.
- 3Watch the pawn breaks — both yours and your opponent's. In these structures the player who times the central break better usually wins the game.
Typical middlegame structures
The main line leads to a tense centre: the central pawns still face each other, and the timing and manner of the coming exchange shapes the whole middlegame. No files have opened yet, so this is a manoeuvring struggle: improve your pieces and prepare the pawn break that will open the position on your terms.
Traps & tactical motifs
Every sharp opening has its traps — study the forcing lines around the centre and the f7/f2 squares before playing this in rated games.
Watch the typical motifs: pins against the pinned piece, knight forks after the natural captures, and queen sorties to a2/g2-style squares.
How to Play Against the KID, Petrosian 8.Bg5
- As White, resolve the central tension on your terms: force the exchange that gives you the better structure rather than letting the opponent choose the moment.
Reaches the same position as
These openings arrive at the very same board position by a different move order — a transposition. Knowing them lets you steer between systems and recognise when your opponent has walked into familiar territory.
Study plan & who it's for
This is serious theory territory: sharp forcing lines and precise move orders. Recommended for ambitious Black players from 1800 upwards.
Play through the main line above until the piece setup feels natural.
Learn the two or three critical pawn breaks for both sides.
Drill one variation at a time — always connecting moves to plans.