Some time ago, I was playing last board in the Belgian teamcontest. My team and the opponents' were struggling at the bottom, fighting for every point to avoid being transfered to a lower league. Anyway, our opponents had strenghtened themselves with the services of GM Vladimir Baklan, with a rating of 2620 number 166 in the world.
Our first board got crushed by this famous GM, and so did I on board 8, loosing a complicated Leningrad Dutch.
After the game, at the bar, I cornered GM Baklan and tried to sell him my book "Attack with the Blackmar Diemer". He is from Ukraine, so I started the discussion on Ignatz Von Popiel, a polish-ukrainian player. At least I got his attention.
He knew quite well about the Blackmar Diemer, and showed negative feelings about our gambit, indicating that the initiative did not outweigh the pawn.
We grabbed a board and he quickly showed me what he would play. Since he showed the line so quickly, I believe this was lingering in the back of his head, maybe even once prepared.
Guido De Bouver - GM Vladimir Baklan
1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bf5 6.Ne5 c6 7.g4 Bg6
Here my famous opponent paused and said "and where is the white initiative ?"
I proudly played 8.h4 ( for sure he would understand my initiative now... )
His response 8...Nbd7 was played equally fast.
Luckily I remebered the refutation 9.Qe2 !!!
Now my GM opponent's attitude started changing. He started playing several moves, only to take them back after a short analysis. He then concluded with "Ok, white does have some compensation". What he actually meant was that black is lost in this line, eg
9...Nxe5 10.dxe5 Nd5 11.h5 Nxc3 12.bxc3 Qa5 13.Bb2 and white is better.
9...Nb6 10.h5 Bxc2 11.Qxc2 Qxd4 12.Qf5 and white is better
9...h5 10.Nxg6 fxg6 11.Bg5 and white is better once again
9...Qa5 10.h5 Be4 11.Nc4 winning
After the offhand analysis, my GM said that he might have to consider 5...g6 instead of 5...Bf5. But analysing the lines, no, enough. Of course I would never be able to win a game against him in one of the above "won" positions. But still, it only shows that the Blackmar Diemer is a serious chess opening, with white having a clear compensation for the sacrificed pawn.