user14202: Evaluation of exchange sacrifice: How good is White's compensation after the exchange sacrifice on move 19?  Seems the position is about even to me but Black might have more issues to solve.  I am thinking it is Whites best winning chance as opposed to having just liquidated the queen-side pawns.
[FEN ""]
1.c4 Nf6 2.Nc3 g6 3.g3 Bg7 4.Bg2 O-O 5.e4 d6 6.Nge2 c5 7.O-O Nc6 8.d3 a6 9.h3 Rb8 10.a4 Ne8 11.Be3 Nd4 12.Rb1 Bd7 13.b4 Ne2 14.Nxe2 cxb4 15.Rxb4 b5 16.cxb5 axb5 17.Qb1 Nc7 18.Rc1 Na6 19.Rb5 Bb5 20.axb5


user14079: This exchange sacrifice would be good if you could coordonate your pieces in order to support the passed b-pawn. In this given position, however, it looks like you are one tempo short and the pawn will be a target: 20...Qa5 and then 
21.Nd4 [21.Nc3 is quite the same] Bxd4 22.Bxd4 Rxb5 and Black should win.
21.b6 Nc5 22.Bxc5 dc5 23.b7 [I see nothing else to hold on the pawn] Qa7 [or 23...e5 to prevent the opening of the g2-b7 diagonal] 24.e5 Bxe5 and the big passer gives practical chances but Black is clearly for choice.
Probably White would have reached a much better version of the game with 18.Nd4!? instead of 18.Rc1.

14202: <p>Evaluation of exchange sacrifice: How good is White's compensation after the exchange sacrifice on move 19?  Seems the position is about even to me but Black might have more issues to solve.  I am thinking it is Whites best winning chance as opposed to having just liquidated the queen-side pawns.</p>

<pre><code>[FEN ""]
1.c4 Nf6 2.Nc3 g6 3.g3 Bg7 4.Bg2 O-O 5.e4 d6 6.Nge2 c5 7.O-O Nc6 8.d3 a6 9.h3 Rb8 10.a4 Ne8 11.Be3 Nd4 12.Rb1 Bd7 13.b4 Ne2 14.Nxe2 cxb4 15.Rxb4 b5 16.cxb5 axb5 17.Qb1 Nc7 18.Rc1 Na6 19.Rb5 Bb5 20.axb5
</code></pre>
 14079: <p>This exchange sacrifice would be good if you could coordonate your pieces in order to support the passed b-pawn. In this given position, however, it looks like you are one tempo short and the pawn will be a target: 20...Qa5 and then </p>

<p>21.Nd4 [21.Nc3 is quite the same] Bxd4 22.Bxd4 Rxb5 and Black should win.</p>

<p>21.b6 Nc5 22.Bxc5 dc5 23.b7 [I see nothing else to hold on the pawn] Qa7 [or 23...e5 to prevent the opening of the g2-b7 diagonal] 24.e5 Bxe5 and the big passer gives practical chances but Black is clearly for choice.</p>

<p>Probably White would have reached a much better version of the game with 18.Nd4!? instead of 18.Rc1.</p>
