13..Rxe3!?

<By sacrificing the exchange (the first defensive procedure) for White's (future) central striker, Black at the same time guarantees himself permanent control of e5, which enables himself to blockade (the second defensive procedure!) the centre and White's kingside.>

17..Ne8

<Passive defence, allowing Black to commence blockading action. After the outwardly more active 17..Ne5, the d6-pawn would have been inadequately supported and the knight at f6 not too secure. Now, in addition, the invasion square c7 is prophylactically defended...>

20..h5

<Of course, this is not an attacking move, but simply... prophylaxis. The possible advance of the white g-pawn to g5 with control over f6 has been nipped in the bud. And, given the opportunity, Black intends to strengthen the blockade on the dark squares, by placing his pawn at h4 and hence controlling g3.>

21..Nh7

<Preparing a prophylactic defence of the slightly weakened g6-pawn.>

24..Bd7

<It would have been a bad mistake to exchange on d4. The doubling of White's pawns would have been an insignificant prize to pay for the lifting of the blockade and the increased activity of his pieces.>

25..Bg7

<Black continues to maintain the status quo.>

26..Rb8

<In anticipation of an attack on the b7 pawn - which will happen sooner or later - Black prophylactically defends it.>

28..Be8!

<By overprotecting his g6, Black forestalls a possible sacrifice here with a strong attack.>

29.e4

<Convinced that there is no prospect of an attack on g6, White switches to the idea of the e4-e5 breakthrough.>

29..N6d7

<It too is forestalled!>

30..Ne5

<Delaying the invasion of the rook at c7 and preventing the invasion of the queen at b6, which, in view of the weakness of the d6-pawn, would have hindered the regrouping of the black pieces.

36..Bxe5

<For the third time, but by no means the last, the bishop appears at e5. Its blockading strength has grown to the maximum, even though White now penetrates onto the seventh rank.>

39.R1c2

<Now the threat of a counterattack on the dark squares restricts the white queen, and does not allow it to go to the queenside. For example, 39.Qa7 Qg3, and White cannot take either the rook or the b7-pawn because of 40..Bd4+ 41.Kh1 Be5 42.Kg1 Bd4+. Nevertheless, Kasparov himself called 39.R1c2 a 'sound time-trouble' move, and an alternative suggestion of his is given at the end of the game.>

45..a5

<The time has come to switch to more active defence. If White accepts the pawn sacrifice (46.bxa5 bxa5 47.Rxa5) he opens a way for the black rook into his position.>

51..Kg7

<Black again sticks to waiting tactics.>

52.Rf2 Bf6

<Breaking the combined 'glances' of the white pieces at f7 (in reserve White still has Be6 in combination with Rc7 and Qa7).>

58..Rd8

<Of course, not 58..Qxa7 59.Qxf6+, breaking through the defensive barriers with an easy win.>

62.Qxe5

<In principle, a major achievement for White. He has forced the exchange of queens and rid himself of the spectre of a counterattack, but... The blockaded nature of the position is retained, and will the exchange advantage suffice for a win?

63..Bd7! 64.Be2

<At this point White evidently decided that after the exchange of bishops Black would tie up his opponent's forces by a counterattack on the b4-pawn.>

70.Bxb5

<Winning also a pawn, but as compensation both black bishops become threatening.>

83..Bd7

<Draw agreed.

Karpov vs Kasparov, 1990