A position very similar to Bertok - Fischer from previous lesson. Again, Black is pushing c4 to nail b2 pawn on its starting position. Possible drawbacks were mentioned before - White gets d4 square for its pieces and Black can be vulnerable to e4 breach. Still, playing c4 here makes perfect sense because White will be busy defending b2 pawn and he won't be having time to reach d4 with the Knight.
16...c4
17.Be2
It takes away desired e2 square for Nc3, but White wants to organize counter-pressure against backward d5. [17.Bc2
with idea Ne2-d4 17...Rab8
18.Rb1
a5
19.Ne2
Qb4
20.Nd4
Rb6
with Ne4 and Rfb8]
17...a5
[17...Rab8
18.Rc2
Bf5
19.Rd2
is holding. a5 is always useful move for Black in similar situations, idea is Qb4 and if White takes, Black will recapture with the pawn.]
18.Rfd1
Qb4
19.Rd4
Rfd8
[Premature is 19...Qxa3
20.bxa3
Rab8
21.Bf3
Rfd8
22.Rcd1
because even if with doubled pawns, White has eliminated his only weakness and is ready to press strong against d5. White will also get b-file while Black Rooks are tied for defence.]
20.Rcd1
Rd7
21.Bf3
Rad8
22.Nb1?
A mistake which drops bind on d5 and allows Black to regroup. [Better was 22.Kf1
h5!
with idea g5-g4 to kick the Bishop off the long diagonal and release one of the pieces tied for d5. (22...g5
23.g4
) ]
22...Rb8
23.R1d2
Qxa3!
[23...Rdb7
might be too slow because Knight goes back to c3 24.Qc3!
Qxc3
25.Nxc3
Rxb2
26.Rxb2
Rxb2
27.Bxd5
Nxd5
28.Nxd5
Rxa2
29.Rxc4
g6
30.e4
and White keeps some chances]
24.Nxa3
Kf8
[But no 24...Rdb7
25.Nxc4
dxc4
26.Rd8+
]
25.e4
dxe4
26.Rxd7
Nxd7
27.Bxe4
Nc5
28.Rd4
Nxe4
29.Rxe4
Rxb2
30.Nxc4
Rb4
31.Nd6
Rxe4
32.Nxe4
Bxa2
and Black won this endgame *