17. ...                  R-Q3
18.  R-QB1               R-R3

Now White must again provide against Black’s Kt-K5, as White’s QKt is needed for the defence of QR2.

          19.  P-B3 R-Q1

Black intends to move his B and then to advance his KP with an attack on the Queen.  The object of the text move is to prevent White from saving himself by an attack on the Rook (Q-B5).

          20.  R-B2 BxKt

By this exchange Black achieves his object of driving off the Knight by P-Q5, but White has time to give his RP further protection by P-QKt3, This, Black would have prevented by playing B-Kt4 instead of the text move, e.g. 21.  P-B4, P-K4; 22.  Q-B5, PxKt; 23.  PxP, B-B3; 24.  PxKt, P-Q5, etc.

21.  PxB P-K4 22.  Q-Kt4 PxP 23.  QxP Kt-K3 24.  Q-K5

This delays the fatal advance of the QP for one move.

24. ...  P-QKt4 25.  P-QKt3 P-Q5 26.  Kt-K4 P-Q6 27.  R-Q2 Kt-Q5 28.  R-QB1 Kt-B7 29.  Q-Kt2 Kt-R6ch 30.  K-R1 Kt-B7ch 31.  K-Kt1 Kt-R6ch 32.  K-R1 Kt-B7ch 33.  K-Kt1

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

Diag. 154

Black does not play for a draw, but only wishes to gain time.

33. ...  R-QB3

The intention is to double Rooks and to force an entry at B7.  P-Kt5 would not be good.  The White Rook would no longer be attacked, and the Knight could attack the QP.

          34.  R(B1)-Q1 KR-QB1

Now that the White Rook has left the QB file, one Rook would be sufficient to force an entry at B7, and Kt-R6ch followed by P-Kt5 could have been played at once, e.g. 34. ...  Kt-R6ch; 35.  K-R1, P-Kt5 (preventing P-QKt4); 36.  Kt-B2,R-B7; 37.  RxR, PxR; 38.  R-QB1, Q-Kt3; 39.  Kt-K4, R-Q8 followed by RxRch, Q-Q5ch and P-B8 mate.

35.  RxP            Kt-R6ch
36.  K-R1           P-Kt5
37.  R-Q7           Q-K4!!

If QxQ, Black mates in three.

38.  R-Q8ch        RxR
39.  RxRch         K-R2
40.  R-Q1          QxQch

Curiously enough there is nothing better.  Q-B2 only leads to the exchange of Queens and the same end-game, which, however, is an easy win for Black, as the permanent mating threat keeps the White Rook tied to the first rank, whilst the Black King threatens to capture all the White pawns.