O’Kelly-Najdorf, Dubrovnik 1950:
Black to play.
Black is under fire on c7! How should he respond?
He could take on b5, but that may allow White to
use the resultant half open c-file to trouble
further c7. Obviously, such harassment would first
require kicking back the c5 knight through a timely
b2-b4. 
Black to play.
Alternatively, he could take on d5. This option is
attractive because after exd5, the g2 bishop is
solidly hindered (cxd5 hangs b5 and Rxd5 forsakes e4
(… Bc6)). He could then take on b5 and make plans to
own enviable c5. The procedure would involve disabling
Bxc5 and b2-b4 through … a3!
Silicon Suspire!?:
18 ... Nxd5 19 exd5 Bxb5 20 cxb5 a3
21 Bd4 Bxd4 22 Rxd4 axb2 23 Qxb2 b6
24 Rd2 Qf5 25 Re2 Nd3 26 Rxe8+ Rxe8
27 Qc2 Qe5 28 Rd1 Nc5.
18 ... Nxd5 19 exd5 Bf5 20 Qd2 Rxe3
21 fxe3 Be5 22 e4 Nxe4 23 Bxe4 Bxe4
24 Re1 Bf5 25 Rxe5.
18 ... Bxb5 19 cxb5 a3 20 Bd4 Nxd5
21 Bxg7 Kxg7 22 Rxd5 axb2 23 Qxb2+ f6
24 Qc2 Re6 25 b6 h4.
18 ... a3 19 Ndxc7 axb2 20 Rab1 Bxb5
21 Nxb5 Ncxe4 22 Bd4 Re6 23 Qxb2 Nc5
24 a3 Ra4.
18 ... Na6 19 Ndxc7 Nxc7 20 Nxd6 Qb8
21 Nxe8 Qxe8 22 Bf4 Ne6 23 Bd6 Bc6
24 c5 Rc8 25 f4.
18 ... Ne6 19 Ndxc7 Nxc7 20 Nxd6 Qb8
21 Nxe8 Qxe8 22 Bf4 Ne6 23 Bd6 Bc6
24 c5 Rc8 25 f4. 
18 ... h4 19 Ndxc7 Bxb5 20 Nxa8 Ncxe4
21 Nb6 Qc7 22 Qd3 Bc6 23 Re1 hxg3+.
18 ... Ra5 19 Nbxc7 Nxd5 20 Nxd5 Bc6
21 Rac1 Ra6 22 Bf4 Bxd5 23 Rxd5 Qe6 24 Rcd1 h4.
18 ... Re6.
LEARN MORE ABOUT THE KING'S INDIAN DEFENSE
King's Indian Defense: White Square Weakness?
King's Indian Defense (Classical Variation): Brawny Bishop
King's Indian Defense (Classical Variation): Sounds of Sound
King's Indian Defense (Benko System): Logical Lunge
King's Indian Defense (Yugoslav/Panno Variation): Pretty Passed Pawn
CHESS OPENINGS ON-DEMAND
King's Indian Defense Electronic Book (E-Book) Part I
King's Indian Defense Electronic Book (E-Book) Part II
King's Indian Defense: Deflect and Declare!
English Opening: Airy Advances
Position after 11 Qc2.
How should Black proceed in this position?
Attacking the kingside isn’t a reasonable
option given he’s got only the f6 knight
and c8 bishop aiming in that direction.
What’s more, White has no weaknesses there.
In the center, both knights draw appreciable
water, therefore there’s hope for a game plan
there. Since there aren’t any easy posts or
shortcomings to go for, Black is forced to
initiate action via a central push (… d6-d5).
Such a thrust also guarantees space and likely
open files for the rooks. But only if c5 wasn’t
hanging following … d6-d5, only if, only if…
But wait! The following imaginary set-up
is so ideal for achieving … d6-d5:
Although in the time it takes to get such a
position White could cook up trouble.
Position after 11 Qc2.
From his point of view, f2-f4 is the game plan
and it’s definitely an easier one to achieve
(12 O-O 13 f4). But 11 … b6 in pursuit of the
imaginary set-up above may still be viable.
Position after 11 ... b5.
On the queenside, Black can gain space and
also give White a backward c3 pawn by
11 … b5 12 cxb5 cxb5. He can then pressurize
c3 down the half open c-file by first moving
the bishop and then placing a rook on c8.
Since the 11 … b5 plan is more rapidly executable
than the 11 … b6 one, 11 … b5 it is! And Bxc5 isn’t
threatening because following … dxc5 the backward
d3 pawn looks tempting down the just opened d-file.
Silicon Suspire!?:
Position after 11 Qc2.
11 ... a6 12 0-0 b5 13 d4 Nb7
14 f4 bxc4 15 Rae1 Qd7 16 h3 c5
17 Rb1.
11 ... Qa5 12 Bb4 Qa6 13 a4 Be6
14 Bxc5 dxc5 15 0-0 Qa5 16 Rab1 b6
17 f4 Bg4.
11 ... Be6 12 0-0 Qa5 13 Bb4 Qa6
14 Bxc5 dxc5 15 a4 Qa5 16 Rab1 b6
17 f4 Bg4.
Position after 11 Qc2.
11 ... b5 12 cxb5 cxb5 13 0-0 Qb6
14 d4 exd4 15.e5 d3 16 Bxc5 dxc5
17 Qxd3 Rd8 18 Qc2.
11 ... Qb6 12 0-0 Qa6 13 Bxc5 dxc5
14 f4 Ng4 15.Qd2 exf4 16 gxf4 f5
17 Ng3 fxe4 18 Nxe4.
Position after 11 Qc2.
11 ... Bg4 12 0-0 Qd7 13 f4 b6 14 f5 d5
15 Bxc5 bxc5 16 h3 Bxe2 17 Qxe2 d4
18 cxd4 Qxd4+ 19 Kh2 Rab8.
11 ... Bd7 12 0-0 Qa5 13 Bb4 Qb6 14 a4 Qc7
15 f4 a5 16 Bxc5 dxc5 17 Rab1 exf4 18 gxf4.
11 ... Qc7.
