Complacency can be fatal in endings

Many a time, a one pawn advantage in the endings may not prove sufficient to win, especially with rooks on board or opposite coloured bishops on board. However, there is many a tendency for complacency to set in and make a move without much thought on many occasions.

In the game which follows, White enjoys the upper hand but just when the players are reaching a double bishop and rook each ending, a blunder by Black ends the game abruptly in White’s favour. Black, without much thought, thinks that he is forcing the exchange of rooks but overlooks a simple pawn move which results in the loss of a piece.
White: Evgeny Sveshnikov (2541) – Black: Suat Atalik (2598)
Bled, 1999

French Defence
1.e4 e6 2.d4 d5 3.e5
The advanced variation of the French Defence
3. .. c5 4.c3 Nc6 5.Nf3 Bd7 6.Be2 Nge7 7.Na3 cxd4 8.cxd4 Nf5
This is one of the often played continuations
9.Nc2 Rc8
The usual played move here is 9. ..Qa5+  10.Bd2 Qb6
10.0–0. If 10.Bd2 Qb6 11.Bc3 Na5
10...Qb6 11.g4
An aggressive advance
11. ..Nfe7 12.Nh4. If 12.Nfe1 h5 13.gxh5 Nf5 14.Be3 f6 15.Nd3 Nxe3 16.fxe3 fxe5 17.dxe5 Qc7 18.Rc1 Nxe5 19.Nd4 Nc6 20.Bg4 Rh6
12...Ng6 13.Ng2. If 13.Nxg6 hxg6  14.Rb1 Be7. 13. ..f6 14.exf6 gxf6 15.Kh1
The king gets away from the diagonal. If 15.f4 f5 (15...Bd6 16.f5 exf5 17.gxf5 Nge7) 16.gxf5 exf5 17.Bf3 Nce7 18.Re1 Bg7 And if 15.h4 Bd6 16.Bh6 Bf8
15...Bd6. If 15. ..Rg8  16.f4 f5  17.gxf5 And if 15...Bg7 16.f4 f5 . 16.f4. If 16.b3 Qc7 and if 16.Bh6 Bf8 17.Be3 Bg7
17...Nce7 17.Qd3 f5 18.Nce3
Incidentally White offered a draw here which was refused
18...fxg4 19.Nxg4 Nf5. If 19...0–0 20.Ne5 Bxe5 21.dxe5 Nf5 is better for Black. 20.Nf6+ Ke7
A colossal blunder! Black walks headlong into the only existing trap. Black could have simply maintained his advantage with 20...Kd8 21.Rd1 Bc6 22.Bg4 Be7 23.Bxf5 exf5 24.Nh5 Rf8
21.Qxf5. White is quick to seize the opportunity
21. .. exf5
Perhaps Black should have seriously looked at  21...Qxd4 22.Nxd5+ (22.Be3 Qxf6 (22...Qxb2 23.Nxd5+ exd5 24.Qxd5 Bc6 25.Qg5+) 23.Qxf6+ Kxf6 24.Bd4+ Kf7 25.Bxh8 Rxh8) 22...Qxd5 23.Qxd5 exd5 24.f5 Ne5 25.Bg5+
22.Nxd5+. Catching the King and Queen in a fork
22. .. Kf7. If 22...Kd8 23.Nxb6 axb6
23.Nxb6 axb6 24.Bf3 Rhe8
Black could have offered more resistance with 24...Bc6 25.Bxc6 Rxc6
25.Bxb7 Rc2. Invading the seventh rank. 26.a4
White could also have looked at 26.h4
26. ..Ree2. Both the black rooks are now patrolling the seventh rank but it is still not enough for Black to get out of trouble
27.Bf3. If 27.Ne1 Bc6+ (27...Rxh2+ 28.Kg1 Rxc1 29.Rxc1 Rh4 30.Ng2) 28.Bxc6 Rxc6. 27...Rf2 28.Rxf2 Rxf2 29.Bd5+ Be6 30.Kg1
If 30.Bxe6+ Kxe6 31.Kg1 Rf3
30...Rc2 31.Bf3 Rc4 32.Be3 Rb4 33.a5
Intersting move! If 33.d5 Bd7
33...bxa5 34.Rxa5 Rxb2 35.Ra6
If 35.Ra7+ Ne7 36.d5 (36.Bh5+ Kf6) 36...Bc8. 35...Be7 36.Ra7
Diagram 1
36. .. Ra2. A big blunder by black which firmly shuts the game for him, If 36...Bc4 37.Bc6 Ke6 38.Bd7+ Kd6 And if  36...Nf8 37.d5 (37.Bh5+ Ng6 38.Nh4 Rb1+ 39.Kf2 Rb2+ 40.Kg3 Rb3)
37.d5
And Black resigned for if 37.d5 Rxa7 38.dxe6+ Kxe6 39.Bxa7.  1–0
Diagram 2
White to play and win
1.Nb6+ cxb6 2.Be6 and White wins.