It's important to build on the advantage

However it is equally important to evade the moves which might appear natural or benign but in reality could be termed as a losing move.

In the game which follows, Black is in a very good position to sight victory for a long time but fritters away his advantage and unfortunately plays what can be called the losing move on the 46th turn.

White: Manuel Apicella (2501) – Black: Emmanuel Bricard (2506)
Besancon, 1999

French Defence

1.e4 e6
The French Defence
2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.f4 c5 6.Nf3 Nc6 7.Be3 cxd4 8.Nxd4 Bc5 9.Qd2 0–0 10.0–0–0
Following book theory till now but things can get interesting as players have castled on opposite flanks
10. ..a6 11.h4 Bxd4 12.Bxd4 b5 13.h5
The pawns have started advancing on opposite flanks
13. ..b4 14.Ne2 a5 15.Kb1
Getting out of the diagonal. If 15.h6 g6 16.Ng1 Nxd4 17.Qxd4 Ba6 18.Bxa6 Rxa6
15...a4
Black’s pawns have advanced quite bit. If 15...Ba6 16.h6 g6 17.Rh3 a4
16.Nc1
If 16.Rh3 Ba6 17.Bf2 Qe7 18.Nd4 Na5 19.Nb5 Rab8 20.Nd6 Bxf1 21.Rxf1
16...Ba6 17.g4 Qc7 18.Rh2 Rfc8
Getting the pieces into position for an attack
19.Bxa6 Rxa6 20.h6
White is also testing Black’s defence
20. ..g6  Black is in a good position
21.Re1 b3
Sacrificing the pawn as the White King looks vulnerable and Black’s pieces are in good position. However Black also had a couple of good moves in 21. ..Qa5 and 21. ..Nxd4
22.cxb3
If  22.axb3 Nxd4 23.Qxd4 axb3 24.Nxb3 Rca8  22...axb3 23.Nxb3 Rca8
Doubling the rooks to pose more problems for White
24.Nc1 Nxd4 25.Qxd4 Ra4 26.Qd2
If 26.Qe3 Qa5 27.Rd2 Nc5
26...Nc5 27.Rhe2 Ne4 28.Qd3 Qa5 29.Rxe4
White decides to sacrifice the rook for this central knight
29. ..dxe4 30.Rxe4 Rxa2
Black returns the favour by sacrificing his rook for the knight. If 30...Rxe4 31.Qxe4 Rc8 32.a3 Qd2 is also better for Black
31.Nxa2 Qxa2+ 32.Kc2 Rc8+
The White King is out in the open and Black’s attack is looking good
33.Kd1 Qa1+ 34.Ke2 Qxb2+ 35.Kf1 g5
Worth a look is 35...Qc1+ 36.Kg2 Rc2+ 37.Re2 Rxe2+ 38.Qxe2 Qxf4 39.Qd1 Qxh6 40.Qd8+ Qf8 and Black can keep up the pressure
36.Re2  If 36.Qf3 Qd2 37.Rc4 Rb8 38.Qe2
36...Qc1+ 37.Kg2 gxf4
If 37...Qxf4 38.Qf3 Qxf3+ 39.Kxf3 Rc3+
38.Rd2 f3+  Black has frittered away his advantage and the position is equal now
If 38...Rf8 39.Qd8 f3+ 40.Kh2 Qb1 41.Qf6 Qg6 42.g5
39.Kf2 Qc7 40.Kxf3 Rf8 41.Qd4 Qb7+ 42.Kg3 Qe7 43.Rf2 Qg5 44.Qf4 Qxf4+
If 44...Qg6 45.Qf6
45.Rxf4 Ra8 46.Rb4
Diagram 1
46. ..f6
Black finds the losing move!  Black could have tried for a draw with 46...Kf8 47.Kf4 Ra7 48.Kg5 Ke7 49.Rb8 Rc7 50.Rh8 Rc5
47.exf6 Kf7 48.g5 Kg6 49.Rb5 Ra7
If 49...Ra4 50.Kf3 Rc4 51.Ke3! Ra4 52.Rb8 Ra7 53.Rg8+
50.Rc5 Rb7 51.Ra5 Rb3+ 52.Kf4 Rb4+ 53.Ke3 Rb8 54.Kd4 Rb7 55.Kc5 Rd7 56.Kc6 Rd8 57.Rb5 Rd1 58.Rb8+- Rd5 59.Rg8+ Kf7 60.Rg7+ Kf8 61.Rxh7 Rxg5 62.Rg7 and Black resigned.
Diagram 2
Black to play and win
1... Rxf3 2.Qxe2 Rxf1 checkmate.

Manisha Mohite