King's Indian Defense: Petrosian Variation, Keres Defense

King's Indian Defense: Petrosian Variation, Keres Defense

Definition

The Petrosian Variation arises in the King’s Indian Defense after White locks the center with 7. d5. When Black immediately replies with 7…c6!?, the line is called the Keres Defense. The full move-order is:

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. d5 (Petrosian Variation) 7…c6 (Keres Defense)

Strategic Concept

• White (Petrosian System): By advancing d4-d5, White clamps the center, restricts …f7-f5, and prepares a slow queenside expansion with b2-b4 and c4-c5. Knights often re-route via d2–c4–e3 or e1-d3-f2 to bolster the center.
• Black (Keres Defense): Paul Keres’s …c6 counterstrike immediately challenges White’s space advantage. After 8. O-O cxd5 9. cxd5, Black has cleared the c-file and can pressure d5 with …Na6–c5 or …Re8–Nd7–f5. The resulting positions are less “closed” than in the traditional …a6/…Na6 lines.

Typical Move Order

8. O-O cxd5 9. cxd5 Na6 10. Be3 Ng4 11. Bg5 f6 12. Bh4 Nh6
— both sides have developed typical piece placements:

• White bishop on e3 or g5 controls the long diagonal.
• Black knight on g4 (or e8–c7–a6) eyes the c5 and f2 squares.

Plans & Ideas

1. White
   • Advance b2-b4-b5 gaining queenside space.
   • Open the a-file with a2-a4, targeting the a-pawn Black often created with …a7-a6.
   • Break with c4-c5 at the right moment to open lines toward the c- and d-files.
2. Black
   • Pressure d5 by piling up on the c- and e-files, or playing …Na6-c5.
   • Prepare …f7-f5 (sometimes after …Nh5) to generate kingside play.
   • Utilize the half-open c-file for counterplay with …Rc8 and …b7-b5.

Historical Significance

• The name “Petrosian Variation” honors World Champion Tigran Petrosian, whose positional style pioneered the 7. d5 idea.
• Estonian legend Paul Keres introduced the immediate 7…c6 in the early 1950s, giving the counter-system his name.
• The variation gained popularity after the 1963–1966 Candidates cycles, when players sought alternatives to heavily analyzed main lines with 7…Na6 and 7…a5.

Model Games

• Petrosian – Keres, Tallinn 1952 — the debut of the line. Petrosian’s positional squeeze was ultimately repelled by Keres’s timely …f5 break.
• Kasparov – Smyslov, Moscow 1981 — Kasparov shows a dynamic pawn sacrifice with 12. b4!? to seize the initiative on the queenside.
• Aronian – Radjabov, Wijk aan Zee 2007 — modern heavyweights test cutting-edge plans, resulting in a sharp tactical draw.

Try exploring the opening directly in your browser with the interactive game below:

Interesting Facts & Anecdotes

• Petrosian reportedly started playing 7. d5 to “take the fun out of the King’s Indian” for aggressive opponents, yet the Keres Defense puts the game right back into tactical territory!
• In his classic book My System in the 1970s, Ljubojević described 7…c6 as “a punch in the stomach to the positional d5-wall.”
• Computer engines initially disliked Black’s space concession, but with modern depth the line is considered perfectly sound and is featured in many top-level repertoires.

When to Choose the Keres Defense

Employ 7…c6 if you prefer:

• A direct challenge to White’s center instead of maneuvering behind a locked pawn chain.
• Half-open files for piece activity rather than a slow kingside pawn storm.
• Fresh positions that sidestep the massive theory in the 7…Na6 main line.