Grünfeld Defense: Three Knights Variation, Petrosian System

A solid and flexible chess opening for Black, aiming to counter White's center and create counterplay on the queenside.

The opening is a popular choice among players who prefer a solid and flexible defense as Black. It is characterized by Black allowing White to establish a strong pawn center with pawns on d4 and c4, while Black aims to counter this center with their pawn on d5 and fianchettoed bishop on g7. The Three Knights Variation is a natural development for White, bringing their knights to f3 and c3, and the Petrosian System specifically involves the development of the dark-squared bishop to g5.

This system is named after the former World Chess Champion Tigran Petrosian, who was known for his solid and prophylactic style of play. The idea behind the bishop move to g5 is to pin the Black knight on f6, making it more difficult for Black to challenge White's center with moves like ...c5 or ...e5. Additionally, the bishop on g5 can sometimes be traded for the knight on f6, doubling Black's pawns and creating a long-term weakness.

Black has several ways to respond to this system, including playing ...h6 to challenge the bishop, or ...c6 to support the pawn on d5 and prepare for a potential queenside expansion with ...b5. The opening can lead to various pawn structures and middlegame plans, making it a versatile and interesting choice for both players.