| 21. ........ | R - K 1 |
With this powerful move Black begins, against White's centre, an assault which will soon be shifted against
the King itself. White is afraid to play 22 P - B 3 because of P - B 4.
| 22. P - K 5 | P - K Kt 4 |
To prevent P - B 4. The White Knight is practically pinned, because he does not dare move on account of R × K P.
| 23. P - K R 4 |
This is a sequel to the previous move. White expects to disrupt Black's Pawns, and thus make them weak.
| 23. ........ | P × P |
Though doubled and isolated this Pawn exercises enormous pressure. Black now threatens R - K 3; to be followed by R - Kt 3 and P - R 6 and R 7 at the proper time.