Grünfeld Defense: Three Knights Variation, Petrosian System

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.Bg5

ECO D91

The Grünfeld Defense: Three Knights Variation, Petrosian System is a chess opening line in the Grünfeld Defense complex, reached after 1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.Bg5.

It is catalogued under code D91 in the Encyclopaedia of Chess Openings (ECO).

The defining move Bg5 is chosen by White on move 5.

Study this line with a grandmaster

This position is covered in the Grunfeld Defense course: a GM-authored repertoire you study move by move, then practice against a human-like AI opponent.

Every chess term used here is defined in the chess terms glossary. Browse all opening courses or the full ECO code index.