11.  Q-K2

White should have prevented the further advance of the Black RP by 11.  P-QR4.  This would have been sound policy in any case, as the R file could not have been forced open for the Black Rooks.

11. ...           P-R5
12.  Kt-Q2        PxP

Premature.  The capture is only of value if the file can be held. 
To that end it is first necessary to play B-Kt2 and to occupy the
R file with Rooks and Queen.  After the exchange of Rooks, Black is at a disadvantage for the end-game because of
the inefficiency of the QB.

---------------------------------------
8 | #R |    | #B |    |    | #R | #K |    |
|---------------------------------------|
7 |    |    | #Q |    | #B | #P | #P | #P |
|---------------------------------------|
6 |    |    | #P |    | #P | #Kt|    |    |
|---------------------------------------|
5 |    |    | #P | #P | ^Kt|    |    |    |
|---------------------------------------|
4 |    |    |    |    |    | ^P |    |    |
|---------------------------------------|
3 |    | #P |    | ^P | ^P |    |    |    |
|---------------------------------------|
2 | ^P | ^B | ^P | ^Kt| ^Q |    | ^P | ^P |
|---------------------------------------|
1 | ^R |    |    |    |    | ^R | ^K |    |
---------------------------------------
A    B    C    D    E    F    G    H

Diag. 165

If instead of the text move Black had driven off the Bishop to B1 with P-R6 (13.  B-B3?, P-Q5!; 14.  PxP, Kt-Q4) he could have enforced his P-K4, but in the long run White would have captured the QRP, and remained with a passed pawn on the R file, a powerful weapon for the end-game, e.g. l2. ...  P-R6; 13.  B-B1, Kt-Q2; 14.  KtxKt, BxKt; 15.  P-K4, P-KB3; 16.  P-B4, followed by Kt-Kt1.

          13.  RPxP RxR
          14.  RxR B-Kt2
          15.  P-KKt4

The Black pieces being cut off from the K side, White is free to attack.

15. ...  R-R1 16.  RxRch BxR 17.  P-Kt5 Kt-Q2 18.  Q Kt-B3 KtxKt 19.  BxKt Q-R4 20.  P-B4

in order to prevent the release of the B by the pawn sacrifice P-B5 and P-B4.

20. ...  B-Kt2 21.  K-B2 K-B1 22.  P-R4 B-R3 23.  P-R5 B-Kt2 24.  P-R6 P-Kt3

By advancing his RP White has weakened Black’s KB3, with the constant threat of establishing his Kt there and of capturing the RP.

          25.  K-B1

This move is superfluous and probably dictated by time pressure.  The proper plan is:  Q-QKt2 with the threat of B-B7 or Kt8 and Q-R8ch.

          25. ...  Q-R6
          26.  Q-QKt2

The end-game is a clear win for White.  He plays his Kt to KKt4, threatening to reach B6 or K5.  The effect is twofold.