The defence has a totally different trend, if Black gives up his own KP, but captures the White KP at once. I have already pointed out that White would not mind his KP being taken, in view of the attack on the open King’s file. Let us now consider in which way this attack can be planned. There are two essentially different lines, according to whether Black interpolates P-QR3 or not.
After 3. B-Kt5, Kt-B3; 4. Castles, KtxP; 5. R-K1, Black gets out of it comfortably by playing Kt-Q3, B-K2 and Castles, and White cannot permanently prevent Black’s game from being freed by the advance of the QP. P-Q4 for White on the fifth move is therefore stronger. Black cannot very well exchange the pawns, leaving the King’s file quite exposed, and must submit to White playing PxP, maintaining the pawn at K5 and preventing Black’s P-Q4 for some time to come.
The opening might continue in this way: 5. P-Q4, B-K2; 6. Q-K2, Kt-Q3; 7. BxKt, KtPxB (to make room for the Kt); 8. PxP, Kt-Kt2 (Diagram 25).
Diag. 25
The whole of the manœuvres now centre round Black’s endeavours to force his P-Q4, and White’s attempt to prevent it. Black ultimately gains his point, as will be seen, but at the expense of such disadvantages in the pawn position that it is questionable whether the whole variation (called the Rio de Janeiro Defence) is playable.
9. Kt-B3, Castles; 10. R-K1, Kt-B4 (the Knight is to be posted at K3 to bring the White KKt away from his Q4, whence he prevents the advance of Black’s QP by attacking QB6); 11. Kt-Q4, Kt-K3; 12. B-K3, KtxKt; 13. BxKt, P-B4; 14. B-K3, P-Q4; 15. PxP e.p., BxP. This is the critical position in the Rio de Janeiro defence. Black has succeeded in eliminating the White centre pawn, and sweeps long diagonals with his Bishops, but the advantage cannot be maintained. White exchanges the Bishop at Q6, and there remains a backward pawn, which Black will hardly be able to hold permanently. In practice it has been shown that the end-game should be won by White in spite of Bishops of opposite colours, as Black’s pawn at his QB4 is difficult to defend.
16. Kt-K4, B-Kt2; 17. KtxB (not BxP because of BxB; 18. KtxB, BxP followed by Q-Kt4ch), PxKt; 18. Q R-Q1 and P-QB4.
The game is much more favourable for Black if he first plays 3. … P-QR3, and retains the option of driving the White KB away by P-QKt4, after which P-Q4 can be enforced very soon. 3. B-Kt5, P- QR3; 4. B-R4, Kt-B3; 5. Castles, KtxP; 6. P-Q4, P-QKt4; 7. B-Kt3, P-Q4; 8. PxP, B-K3, 9. P-B3.
Now Black’s pieces are more mobile, and that is the reason why this system of defence is becoming more popular than any other.