A review of the fourth round.

Finally, Black managed to win the first game. Experienced grandmaster Michal Krasenkow seemingly clearly outplayed his younger opponent Moritz Weishäutel in complicated Grünfeld Defence. But only the analysis of the game with the computer enabled me to see the decisive moment.

The computer likes the white position and claims that White should even win here. The simplest way to play is 17.hxg6 hxg6 18.Qd2. If now 18...Bf6, then 19.f4 Kg7 20.g3 Qh3 21.fxe5 Bxe5 22.Bd4+-. The pawn sucrifice is also good: 17.Qd2 Qxh5 18.f3 b5 19.Rf2, which prepares g2-g4 with attack.

In the game Black got more chances and after some dubious moves by the opponent he managed to overtake the initiative. 

17.Ng3?! b6 18.Qd2 Bf6 19.h6 (19.Nh1! Qxh5 20.f3 g5 21.g4 Qg6 22.Ng3) Nb7 20.Ne2 g5 21.f3 Be7 22.g4 Bc5 23.Kg2 Bxe3 24.Qxe3 Qxh6 25.Rh1 Qg7 26.Rh3 Rd6 27.Rch1 h6 28.Ba4 Nc5 29.Bb5 Nd3 30.Bxc4 Nf4+ 31.Nxf4 gxf4 32.Qe1 (32.Qc1!?) Bd7 33.Kf2?! Rc8 34.Bd3 b5 (34...Rg6!?) 35.Qb1?! Qf8 (35...Rg6)

Now White should try 36.Qb4=.

36.Rh5? Rxc3 37.Rxe5 Rg6

Black now starts the attack. It looks as if White has forgotten his king: no one is trying to defend him.

38.d6 Qxd6 39.Rd5 Qb6+ 40.Kg2 Bxg4! 41.fxg4 Rxg4 42.Kf3 Rg3+ 43.Kf4 Qf2+ 44.Ke5 Rg5+ 45.Kd6 Qf6+ 46.Kd7 Qe6+47.Kc8 Rc8#.

White had more luck in the games Heinemann - Vaisser and Koelle- Gaehwiler.  In both games Black missed a draw in zeitnot.

Heinemann - Vaisser (Position after 59.Kd3)

59...Ra3! 60.Kd2 (60.Ke2 Re3+ 61.Kf1 Re8!=) Ra8?

Brilliant 60...Rxf3!! 61.c7 Rf2+ leads to perpetual check. Now it's over.

61.c7 Rc8 62.Kd3+- and Black is in Zugzwang. Noch folgte Bg1 63.Nxf6+ Ke5 64.Rc6 Bh2 65.Ne4 Bf4 66.Kc4 Be3 67.Nd6 Rxc7 68.Rxc7 Kxd6 69.Rf7 Ke6 70.Rf5 Bc1 71.Kd4 Bd2 72.Ke4 Bc1 73.Rc5. 1-0

Koelle - Gaehwiler (Position after 32...Kg8)

33.Bxf5? Looks like a crashing combination, but in reality it offers Black a great chance to escape. Better was 33.g4! and if fxg4, then 34.Rg5+ Kf8 35.Bxh7+-.

33...exf5 34.Rxf5 Rc2?! (34...Ra1+! 35.Kg2 Ne6 36.c7 Ra8 37.Rfxf7 Rd2!=) 35.Rfxf7?! (35.Kg2!?) Rxc6?

Black still could escape with 35...Ra1+! 36.Kg2 Ne6 37.c7 Rac1=. Now his knight stays pinned.

36.Rg7+ Kf8 37.Rxh7 Kg8 38.Kg2 Rc2 39.h4 Rb7 40.Rhf7 Ra7 41.h5 Rc6 42.h6+-. 1-0

Tobias Koelle is now leading with 3 point from 4 games.