10. ...  Q-R5

It now looks as if White were lost.  But a fine sacrifice forces the exchange of all Black’s attacking pieces, and saves the situation.

11.  RxKtch PxR 12.  Q-Q8ch QxQ 13.  KtxQch KxKt 14.  KxB ...

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

Diag. 125

After the terrible slaughter, the position is somewhat clearer.  Black has a Rook and two pawns for two minor pieces, a slight advantage for the end-game, but as yet there is no thought of an end-game.  White, in possession of two Bishops, with an open Queen’s file on which the Black King stands, has good attacking chances, and most masters would think the position favourable for White.

          14. ...  B-K3

P-KB4 is a plausible move, but is followed by a pretty mate by 15.  B-Kt5.  The move in the text threatens to eliminate the KB by P-QB4, P-QKt4.

          15.  B-K3 P-KB4
          16.  Kt-B3 K-K2
          17.  P-KKt4

Tarrasch recommends 17.  R-Q1, threatening Kt-Q5ch.  If P-B3, White could play 18.  B-Kt6, thereby permanently preventing Black from contesting the Queen’s file, and then try to exchange Black’s B by Kt-K2-Q4.  With two Bishops, White would then have winning chances.

A subtle idea underlies White’s move of P-KKt4.  He wishes to take advantage of the fact that Black has exchanged the KB by playing P-Kt5, thus holding all the four pawns on the King’s side.  But Black finds a surprising reply, which seems to refute White’s plan.

Capablanca played against Ed. Lasker (New York, 1915), 17.  P-KKt4, P-KKt3; 18.  K-Kt3, P-KR4; 19.  PxBP, P-R5ch; 20.  K-R2, PxP; 21.  Kt-K2, P-Kt4; 22.  B-Kt3, BxB; 23.  RPxB, KR-KKt1; 24.  R-Q1, QR-Q1; 25.  RxR, KxR; 26.  Kt-K4, winning a pawn.

17. ...          P-KKt3
18.  P-Kt5       QR-KKt1!!

Black offers the exchange in order to get rid of White’s QB.  If White accepts the sacrifice, he loses his KKtP, and Black retains three passed pawns for the piece, at least an equivalent for the end-game.  White should decline the doubtful gift and meet the threat of P-R3 and P-KKt4 with 19.  R-KKt1.