1970, are well-known examples. Black can initiate further kingside activity by playing ...Nd7-e5 followed by ...g7-g5. The pawn move prevents White from driving away the knight with f2-f4, and sets up the possibility of Black bringing a knight on f4 via g6 or h5. Further space-gaining pawn advances such as ...g5-g4 and ...f7-f5 may even be possible. En route to winning his first USSR championship, Tal provided a brilliant example of how Black's dark-square control could lead to a kingside attack. Against Gurgenidze at the 1957 championship in Moscow, he unleashed the double sacrifice 14...Nxf2!! 15.Kxf2 Qh4+ 16.Kf1 (16.g3? Bd4+ 17.Kg2 Qxh3+ 18.Kf3 Bg4+ 19.Kf4 g5+ 20.Kxg5 Be3+ 21.Kf6 Qh6 mate) Bd4 17.Nd1 Qxh3! with the point that 18.gxh3 Bxh3 is mate. After 18.Bf3 Qh2 19.Ne3 f5! 20.Ndc4 fxe4 21.Bxe4 Ba6! White was unable to defend against Black's threats of 22...Rxe4 23.Qxe4 Re8 24.Qc2 Nxd5 and 22...Bxc4+ 23.Nxc4 Rf8+ 24. Bf3 Rxf3+, and Gurgenidze resigned after move 27. White's queenside play When Black prepares the ...b7-b5 pawn break with ...a6, White usually tries to hinder it by playing a2-a4, even though this advance weakens the b4-square. As a further deterrent to Black's queenside expansion, White often moves the knight on f3 to c4 via d2. With the knight on c4, Black's ...b7-b5 break may be met by axb5 followed by Na5, when the arrival of a white knight on c6 could severely disrupt Black's position. The knight on c4 also attacks Black's backward pawn on d6, and White can often increase the pressure on this pawn by playing Bf4 or Nb5. The strength of White's knight on c4 often induces Black to exchange it off: typical ways of doing so are ...Nb6, ...Ne5, or ...b7-b6 followed by ...Ba6. Even if Black should succeed in enforcing the ...b7-b5 break, White may halt the b-pawn's further advance by simply playing b2-b4. Even though this would give Black the opportunity to establish a passed c-pawn with ...c5-c4, blockading the queenside in this manner may allow White to pursue play in the centre and on the kingside undisturbed. The ...c5-c4 advance would also relinquish Black's control over the d4-square, which may be occupied to good effect by a white knight or bishop. A successful demonstration of this last idea occurred in the game Pintér–Brynell at the 1998 Elista Olympiad. White answered Black's 21...b5 with 22.b4!, and Black was unable to keep the queenside open