(1) Negi,P (2622) - Moradiabadi,E (2536) [C67]
ch-Asian Individual Mashhad IRI (7.5), 08.05.2011 [Mueller,Karsten]

1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.0-0 Nxe4 5.d4 Nd6 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8 9.Nc3 Ke8 10.h3 h5 11.Bf4 Be7 12.Rad1 Be6 13.Ne2 Rd8 14.Ned4 Nxd4 15.Nxd4 Bc8 16.c3 g5 17.Bc1 Rg8 18.Ne2 Rd5 19.f4 gxf4 20.Rxd5 cxd5 21.Nxf4 c6 22.Be3 b6 23.Rf3 Rh8 24.a4 Rh7 25.Ne2 Be6 26.b4 Kd7 27.Rf1 Rg7 28.Kh2 Rg8 29.Nf4 Rh8 30.b5 Rc8 31.Nxh5 cxb5 32.axb5 Rxc3 33.Bg1 Ra3 34.Nf6+ Bxf6 35.exf6 Ra5 36.Rb1 Bf5 37.Rb3 Bc2 38.Rb2 Bd3 39.Rd2 Be4 40.Rb2 Ke6 41.Bd4 Ra4 42.Rd2 Rb4 43.Kg3 Rxb5 44.Kf4 Rb1 45.g4 a5 46.Rb2 Rxb2 47.Bxb2 b5 48.h4 b4 49.Bd4 a4 50.h5 Bh7 51.Ke3 a3 52.Bc5 0-1 The principle of one diagonal Pure opposite colored bishop endings have a very large drawish tendency. If the defender is dug in on squares of his own bishop his fortress usually cannot be stormed. But no rule without exceptions: why did Negi resign without waiting for Black's answer?

52...d4+!!
Elshan Moradiabadi destroys White's defensive set up in a radical way. [52...Kxf6? 53.Bxb4 a2 54.Bc3+ The bishop controls all important squares on one diagonal and will not fall into zugzwang. 54...Kg5 55.Kf3 Be4+ 56.Kg3 f5 (56...Bc2 57.Bd2+ Kf6 58.Bc3+ Ke6 59.Kf4= ) 57.gxf5 Bxf5 58.Kf3 Kxh5 59.Ke3 Kg4 60.Kd2 Kf3 61.Kc1 Bb1 62.Kb2 Ke4 63.Bg7 d4 64.Bxd4 Kxd4 65.Ka1= ; 52...a2? 53.Bd4= ; 52...Ke5? 53.g5 Kf5 (53...Bf5 54.g6 d4+ 55.Bxd4+ Ke6 56.gxf7 Kxf7 57.Bc5 a2 58.Bd4= ) 54.g6 d4+ 55.Bxd4 Bxg6 56.hxg6 Kxg6 57.Bc5= ]

53.Bxd4
[53.Kxd4 a2-+ ]

53...b3 54.Kd2 b2
Now Black's bishop rules.

55.Bxb2 axb2 56.g5 b1Q-+ 0-1