I was playing in the Belgian interclub competition yesterday in Gent ( the city in Belgium where Diemer played several tournaments ) and faced a tough Gunderam defense. Unfortunately, I was unable to find the correct continuation.
De Bouver - Van Den Bossche, 23-OCT-2011
1.d4 Nf6 2.Nc3 d5 3.e4 dxe4 4.f3 exf3 5.Nxf3 Bf5 6.Ne5 e6 7.g4 Be4 8.Nxf7 !!
8...Kxf7 9.Nxe4 Nxe4 10.Qf3+ Nf6 11.Qxb7
It is widely known that the Belka-Neumeyer line is incorrect against correct play, but here my opponent played something new, a line that did not appear in my book, so it must be inferior, I said to myself, right ...?
Now my opponent played surprisingly 11...Nxg4 !!
The purpose of this move is to give room for the queen check on h4.
12.Qf3+ Nf6 13.Qxa8 Nd5 !!
A second surprise. Black could have played this move already on move 11, so black effectively won the g4 pawn for a tempo.
I now played 14.Be2 (?? - 14.h4 should have won) but came under heavy fire after 14...Qh4+ 15.Kd1 Qxd4+ 16.Bd3 Be7 17.Rf1+ Bf6 18.Qb7. The game eventually ended in a draw, which was a very lucky result for me, since I was completely outplayed by black.
But how should white proceed after 11...Nxg4 or 11...Nd5 ?
After 11...Nxg4, I believe the right move is 12.Qxa8 (diagram), since 12.Qf3+ Nf6 13.Qxa8 allows for 13...Qxd4 with a small black advantage.
...a1/ 13...Qf2+ 14.Kc3
......a1a/ 14...Bc5 15.a4 (+=)
......a1b/ 14...Nd7 15.Qc6 (+-)
......a1c/ 14...Na6 15.Kb3 (+-)
......a1d/ 14...Qe1+ 15.Bd2 Bb4+ 16.Kb3 Qxd2 17.Qf3+ (+-)
......a1e/ 14...c5 15.Qxb8 (+-)
...a2/ 13...Nf2 14.Qf3+ (+-)
b/ 12...Qxd4 13.Qf3+ Nf6 14.Be2 (+=)
The other option 11...Nd5 12.Qxa8 is better for black :
c/ 12...Qh4+ 13.Kd1 Qxg4+ 14.Be2 Qxd4+ (=), transposing in the game I played
d/ 12...Bb4+ 13.c3 Qh4+ 14.Kd1 Bxc3 15.bxc3 Qf2 16.Bd2 (=)
Still, I have to note that this Belka-Neumeyer line is quite dubious, since it is actually refuted. The simple 8.Nxe4 Nxe4 9.Qf3 is probably a much better continuation for the attacker.