Black has solidified his center and now returns to the original plan, namely to attack on the k-side. White's pieces are cramped for space and will find it hard to parry an attck on the k-side and also blockade the dominating Black center pawns. Black's main weakness is the dark squares, which White should seek to exploit.

24. Bxh5 is dangerous in the extreme, as it opens a file straight to the White K. 24. ...Rh8 or ... g4 are both playable, and then the White B is effectively nailed to h5 indefinitely.

Tempting White to play the seemingly aggressive move Qg5.

White charges into the breach. 26. Qd4 would have been met by ... c5, and then Black's central pawn storm is well under way.

This levels the material, but at terrific risk, as Black can now seize control of the h-file with his rooks.

An alternative line was: 28. Kg1, Rxh2; 29. Kf1 (forced), Rh1+: 30. Ke2 (blocking his own R and B), R1-h5 (forcing the White Q to reteat); 31. Qe3, Rd1; 32. Qxa7, whereupon White's lone Q quickly runs out of checks, whereas Black's attack up the center is more likely to hit home due to White's completely tangled position.

33. Ke2?? leads to a quick mate after 33. ...Qf3+; 34. Kd2, Qxc3+; 35. Ke2 (forced) Qd3#. Or 33. Ke2, Qf3+; 34. Kf1, Rh1+; 35. Qg1 (forced), Bh3#.

White has survived Black's k-side attack, but it has cost him another pawn, and this one is a game changer. Black now has a connected passer in the center and a straightforward endgame.

Setting a trap: if 37. Bg4 (which apparently wins the exchange) then ... BxBg4! 38. RxRc1, d4-d3; 39. f2-f3, d3-d2; 40. R anywhere, Bxf3+ and White must sacrifice the R for the Black QP on d1, leaving Black a clear B advantage. White, however, does not fall for it.

The Black B has hardly moved the whole game, but the few squares it has occupied have proven to be very strong, if only latently.