Be calculative when pawn is sacrificed

Chess Checks

 Sometimes pawns are offered to clear up files or diagonals , which makes it easier for the queen, rooks and bishops to join the attack and at times simply to unleash some lethal combination. Therefore it is necessary to examine and carefully calculate when the opponent sacrifices a pawn.

In the game which follows, things are more or less on equal footing in the middle game when White blunders and is tempted by a pawn offer on the 19th turn. Black then wins a piece and has no difficulty in converting the position into a winning one.

White: Sergey Kudrin,S (2525) – Black: Larry Mark Christiansen (2610)
USA, Salt Lake City,1999

French Defence
1.e4 e6
The French Defence
2.d4 d5 3.Nd2 Be7 4.Bd3 dxe4 5.Nxe4 Nf6 6.Nf3 Nbd7 7.0–0
If 7.Qe2 Nxe4 8.Bxe4 c5 9.Be3
7...Nxe4 8.Bxe4 c5 9.c3 0–0 10.Qe2
If 10.Bc2 cxd4 (10...Qc7 11.Re1 Rd8 12.Qd3 Nf8 13.Qe4 Bd7 14.Ne5 cxd4 15.Qxd4 Be8) 11.Qxd4 Nc5 12.Qg4 e5 13.Qh5 e4 14.Rd1 Qc7 15.b4 Nd3 16.Bxd3 exd3 17.Rxd3 a5  
10...Qc7 11.Rd1 cxd4
If 11...Nf6 12.Bg5 h6 (12...Nxe4 13.Qxe4 (13.Bxe7 Nxc3) 13...Bd6 14.Be3 f6 15.Rd2
12.cxd4
White could also try 12.Nxd4 Nf6 (12...Nc5 13.Bc2 b6 14.b4 Nb7 15.Qe4 f5 16.Qf3) 13.Bc2 Rd8 14.Bg5
12...Nf6 13.Bg5 Bd7 14.Rac1
Taking control of open file
14. ..Qb6 15.Ne5 [
As tempting as this move looks, White could have continued more dynamically with 15.d5
15...Bb5 16.Qf3
White’s pieces are all clustered on the King side
16. ..Rad8
A good move!
17.Ng4
White also had a good move in 17.Qh3. If 17.Bxb7 Rxd4 18.Be3 (18.Bc6 Rfd8 19.Rxd4 Qxd4) 18...Rxd1+ 19.Rxd1 Qc7 20.Bf4 Qc2
17...Nd5 18.Bxe7 Nxe7

Diagram 1

19.Bxb7
A terrible blunder! White walks headlong into a very simple trap and ends up losing a piece.
19...Rb8. Bang on target to capitalize on White’s blunder . If 19...Rxd4 20.Ne3 , the position is more or less equal
20.Be4. He hardly has any choice!
20. ..f5 21.Bc2 fxg4 22.Qxg4
Black has won a piece and suddenly his pieces look dangerous
22. ..Qd6 23.Re1 Bd7
If 23...Nf5 24.d5 Bd7 25.dxe6 Bxe6 26.Rcd1 Qb6 gives advantage to Black
24.Qe4
Worth a look is 24.Bb3
24. ..Ng6 25.Bb3 Kh8
Taking time off to take his King to safety. Now White cannot pose any more threats and all that Black has to do is bank on his extra material to score a win.
26.g3 a5 27.Re2 Rb4 28.Bc4 a4 29.b3 Rb6 30.Rce1
Trebling his forces on the central file but it does not help!
30. ..Rf6 31.Qa8+ Rb8 32.Qa7 Rc8 33.Bd3 axb3 34.axb3 Ne7 35.Be4 h6 36.Rd1 Nd5 37.Rc2 Nc3 38.Re1 Nxe4 39.Rxc8+ Bxc8 40.Rxe4
Black has cleverly managed to exchange a few pieces
40. ..Qc6 41.d5 exd5 42.Re7 0-1.
Another big blunder and White realizing it, immediately resigned.  Black can continue with 42. ..Qc1+  43.Kg2 Ba6  44.Qa8+ Kh7  and White is totally lost as  he has to give up heavy material to avert checkmate.

Diagram 2

White to play and win
 1.Rd1. And it is all over for Black
1..Kf8 2.Rd8+ Ke7 3.Rxc8 Kd7 4.Rf8 Kxc7 5.Rxf7+.