Terrible complications in the Vienna defense

In my previous posts, I discussed some interesting possibilities in the Vienna defense occuring after 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 Bf5.

Black declines the gambit by developing a piece.

I showed that the "More than Hara Kiri" gambit occuring after 5.g5 Bg6 6.h4 should not pose any problem for the defender as 6...h6 is a simple and effective defense.

I also proved that white does not get full compensation in the alternative line 5.fxe4 Nxe4 6.Qf3 as 6...Nxc3 7.bxc3 e6 as both 8.Qxb7 and 8.Bd3 are insufficient.

So what should the attacker play in the Vienna ? Let's have a look at 5.g5 Bg6 6.g5. Black best option now is 6...Nd5 7.Nxe4, reaching the basic "Hara Kiri" position.

Let's explore black's most natural move 7...Nc6, threatening 8...e5 ( the alternative 7...e6 is answered by 8.h4 )

Untill recently, 8.c4 Ndb4 9.a3 was dismissed because of the simple 9...Qxd4

But, it seems to me that white can take the black knight after all, eg 10.axb4 Bxe4 11.fxe4 Qxe4+ 12.Kf2 Qxh1 13.Nf1

Now it is very worthwhile to investigate this position since this line is quite forced after 8.c4. Black's queen is trapped on h1 and black needs to be very carfeul to get some compensation for it.

a/ 13...h6 14.g6
...a1/ 14...fxg6 15.Qa4 (+-)
...a2/ 14...f6 15.Qa4 (++)
...a3/ 14...f5 15.Qd5 (++)
...a4/ 14...e6 15.Qa4 (+=)
...a5/ 14...Rd8 15.Qa4 (=)

b/ 13...e6 14.Qa4 (+-)

c/ 13...e5 14.Qa4
...c1/ 14...Bxb4 15.Bg2 Be1+ 16.Nxe1 Qxh2 17.Nf3 Qh5 18.Nxe5
......c1a/ 18...00 19.Nxc6 bxc6 20.Bxc6 (=)
......c1b/ 18...Qh4+ 19.Kf3 (+=)
...c2/ 14...e4 15.Bg2 Qxg2+ 16.Kxg2 exf3+ 17.Kxf3 Bxb4 18.Be3 (=)
...c3/ 14...Rd8 15.Be3 (=)


d/ 13...Rd8 14.Qa4
...d1/ 14...e5 transposing to (c3)
...d2/ 14...e6 (+-)


So I guess the suggested line Vienna defense line 7...Nc6 8.c4 Ndb4 9.a3 Qxd4 10.axb4 provides white with an interesting attack, in which black must choose very precise defensive moves in order to survive.

Other authors ( including Scheerer ) had given black a large advantage after 7...Nc6 8.c4, but this analysis proves the opposite and restores the Hara Kiri line as the main Vienna defense line.Consider that thought as my best christmas present ever !