Not yet equality, but close.

The O'Kelly ( or Ziegler ) defense has been a favorite of the Blackmar Diemer critics. It was even called the refutation of the gambit. An indeed, when white attacks like a madman, black might get the better prospects ( see my earlier blogs "Ziegler innovation" and "Refuted for the wrong reason" ').

But, IM Stefan Bucker published in 2010 on chesscafe.com the right approach ( cfr "O'Kelly variation – 7.Bg5 Nbd7 line" ) 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 c6 6.Bc4 Bf5 7.Bg5.

Today we will look a bit closer at a line from that earlier blog that seems to give black some small advantage 7...Nbd7 8.Qe2 e6 9.000 Be7 10.Bxf6 Bxf6 11.d5 (diagram)

In my earlier blog, I might have given some incorrect information, so I am fixing that right now.

a/ 11...cxd5 12.Nxd5 (diagram)

...a1/ 12...Nb6 13.g4!! (=)
...a2/ 12...Nc5 13.g4!! (=)
...a3/ 12...Bg5+ 13.Kb1 (=)
...a4/ 12...Rc8 13.Rhf1 (=)
...a5/ 12...000 13.Nxf6+ gxf6 14.Bb5 (+-)
...a6/ 12...a6 13.Rhf1 (=)

b/ 11...Bxc3 12.dxe6
...b1/ 12...fxe6 13.Bxe6 (=)
...b2/ 12...Bxe6 13.Bxe6 (=)
...b3/ 12....Bxb2+ 13.Kxb2 (+=)

c/ 11...00 12.dxe6 (+=)

d/ 11...Qc7 12.dxe6 fxe6 13.Bxe6
...d1/ 13...000 14.Bxf5 Qf4+ 15.Kb1 Qxf5 16.Ne4 (=)
...d2/ 13...Qf4+ 14.Nd2 (+-)

e/ 11...Qe7 (diagram)

This seems to be the only line where black could claim a small advantage. In my earlier blog, I indicated that 12.dxe6 was to be preferred over 12.d6, but now I am not so sure anymore. In an y case, my silicon friend gives black a small advantage here ( -0.37 ). Let's investigate 12.dxe6 a bit better :

...e1/ 12...Bxe6 13.Bxe6

......e1a/ 13...fxe6 14.Qe3 (=)

......e1b/ 13...Qxe6 14.Ne4 (=)

...e2/ 12...fxe6 13.Nd4 ( improving on my earlier blog )

......e2a/ 13...000 14.Nxe6 (=+)

......e2b/ 13...Bxd4 14.Rxd4 (=+)

So we have to conclude that there are some lines in the Ziegler defense that give black a very small edge ! talking about a disappointment - but it is up to you to prove the opposite !