The Principle of two weaknesses in Chess -2-

Smyslov -Tal
(1964)

The weakness of the pawn on a4 is immediately apparent. The white king is permanently tied to defending this weakness. On the other wing, the weakness of the g4 square quickly becomes apparent. The king threatens to reach the base of the pawn chain via this square to h3. However, this can be prevented by the pawn move h3.
1. … Kg6
2. Ka3 Kh5
3. h3
There is no way through for the king here. However, the pawn on h3 has now become the second weakness that can be attacked by the bishop. But first, the king returns to its starting point.
3. … Kg6
4. Kb3 Kg7
5. Ka3 Kf6
and now
6. Kb3 Be8!

The bishop wants to attack the pawn on h3 via the route h5-e2-f1. To do so, however, it must allow the white knight access to the squares g2 and f3.
7. Ng2

Smyslow opted for a passive defense here. However, he could also have defended actively
7. Nf3 Bh5 8. Ne5 Bd1+ 9.. Ka3 Ke6! 10. Nc6 Bc2 11.Ne5
                                                           Analysis diagram:

With great difficulty, White manages to defend the attacked pawn weaknesses. But now Black puts White in zugzwang with a so-called triangle maneuver of his king
11. … Kd6 12. Nf7+ Ke7! 13. Ne5 Ke6
Now the knight can no longer move without losing the d-pawn.
The only remaining pawn moves are g4 or h4.
14. g4 would simply be met with 14. ...h6, which would again result in zugzwang. And after 14. h4, there would be another triangle maneuver. If the pawn then moves to h5, h6 follows and Zugzwang prevails again.

7. … Bh5

8. Kc2 Be2

9. Ne1 Bf1

10. Nf3!
Still the best option! Because 9.h4 is hopeless. The bishop returns to c6 and then the king penetrates the position via the weak square g4.
10. … Bxh3!
That is the correct answer! Because h6 would lead to a draw after Ng1.
11. Ng5 Bg2
12. Nxh7 Kg7
13. Ng5 Kg6
14. Kb3 Kh5
15. Ka3 Kg4
Now the two pawns on the kingside fall.

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