TheaN: Saturday 11 April 2015 <22.?>So far I've been on 5/5 this week, something that I haven't been able to attain in quite a while. Hence, I decided to put a bit more thought into the weekend puzzles this week.
White controls the queenside and piece pressure on the center, black expanded on the kingside and holds with the small center. Material is dead even, and the pieces on both sides seem to be decently developed. Black has only one problem, and that is the fragility of his small center. White would want to break on the queenside now in order to abuse the backward pawns on d6 and e6.
This suggest <22.c5!>. Picturing these kind of moves is tricky, but they are logical. By attacking both the queen on b6 and the pawn on d6, white commits black to either surrender the small center or reposition the queen to an infavorable square.
Black can decline, but no square is really great for the black queen:
A) <22....Qc7> bad idea. <23.cxd6> if <23....Qxd6 24.Nxf5 
> black collapses.
B) <22....Qa6> black cannot trade in a worse position <23.Qxa6 bxa6 24.cxd6 Nxd6 25.Rc7 
> white claims the queenside, great pressure on the backward pieces and shortly also a7 & a6.
C) <22....Qd8> does not really challenge white's expanse. <23.Bxb7> and if <23....dxc5> simply <24.Rxc5 > and white is at least up a crucial pawn.
C) <22....Qa5> this move closely follows the accepted line with white having an additional pawn, if it follows <23.Bxb7 dxc5>: c5 is defended, but white can play <24.Nxf5! >. See the accepted line for more details.
If accepted, white follows the principle of variation C.
D) <22....dxc5 23.Nxf5!> black cannot ignore the sudden exposure of the long diagonal. White threatens Bxg7+ or Nxg7, as well as Rxd7. Other important key elements are that if the black queen moves, Rxc5 regains the c-pawn, when black captures the knight with the g-pawn h5 becomes weak and with the e-pawn the center. Bxb2 does not gain much for black after Qxb2+, winning a tempo and weakening the center.
If black tries to block the diagonal he loses:
D1) <23....e5 24.Nxg7 >.
D2) <23....Be5 24.Rxd7>, if 24....gxf5? 25.Rxf7! , if <24....exf5 25.Rxb7 > and the black position collapses.
Capturing on b2 does not work as it forces black to capture with the g-pawn and weaken the center:
D3) <23....Bxb2 24.Qxb2+ e5 25.Rxd7 gxf5 26.Bd5 >
Capturing on f5 is the only possibility, yet the position is weakened:
D4) <23....exf5?!> tries to keep the pawn structure intact but it creates weaknesses in the center similar as in D3 <24.Rxd7> if <24....Rb8> to protect b7, <25.Bd5 > should decide.
D4) <23....gxf5 24.Rxd7 Rb8> for the moment white is not really threatening anything, however, capturing towards the center created a weakness on the kingside. <25.Bxg7+!> all the time black could Bxb2 was not a good move. Now white returns the favor. <25....Kxg7 26.Qh5!> having solved the long diagonal, white can invade on the freshly vacanted square h5. Typical in this position is that white is not necessarily threatening anything, but black's in a complete bind. Black's best try is to counterattack on the queenside <26....Qa5?!> but this leaves e6 unprotected <27.Qg5+ Kh8 28.Qf6+ Kg8 29.Qxe6 > änd white forcefully invades the black kingside.
Kibitzing
