Botvinnik Semi-Slav, The (Pedersen)

THE MAIN LINE: 17 a3 31
19 ... xb7 (D)
19 ... 'ii'xb7? 20 lLlxc5lLlxc5 21 bxc5
~xc5 22 'ii'c2 'ii'd5 23l:[fcl 'ii'xg5 24
'it'xc4 and White wins.
w
20 lLlc3!?
When I told a friend of mine, GM
Peter Heine Nielsen, about this line he
soon came up with this possibility. After
a long analysis session we concluded
it was more or less winning for
White (but we were wrong!). The alternatives
are therefore worth investigating:
a) 20 lLlxc5+ ~xc5 21 bxc5lLlxc5
seems to give Black quite decent compensation.
b) 20 ~f4! 'ii'c6 21 llel currently
looks the most dangerous:
bl) At first, I thought 21...~d6
was quite clever since 22 ~xd6? allows
22 .. .lhh2! 23 lLlxc5+ lLlxc5 24
lle7+ (24 f3 l::tdh8 -+) 24 ... lLld7 25
llxd7+ llxd7 26 xh2 ':xd6, when
Black is probably slightly better. However,
I soon came down to earth when I
realized that 22 b5! 'ii'c7 23 'ii'f3+
b8 24 ~xd6 'it'xd6 25 l:.e7 stops all
tricks and gives White a very promising
game.
b2) 2l...d3 22 b5 'it'xb5 23 lle4
(Lutz recommends 23 b3!?, which actually
does appear very promising:
23 ... cxb3 24lLlc3 'ii'c6 25 'it'xb3+ gives
White a clear advantage) 23 ... lLlb6 24
lLlxb6 axb6 25 lle7+ (Lutz suggests
that White should rather wait and see
what Black has in mind, for example
after 25 h4!?) 25 ... ~xe7 26 'it'f3+
'it'c6 27 l::ta7+ xa7 28 'it'xc6 ~d6! 29
~xd6 d2 30 'it'd5 l::the8 31 'it'xf7+
(this only leads to a draw, so perhaps
White should consider 31 'iii'xd2!?
lle6 32 ~b8+ ':xb8 33 h4!? with an
edge) 3l...'iita6 32 'ii'xc4+ b5 33 'ii'a2+
~b6 34 'iii'd5 llel+ 35 ~g2 dl'it', and
now rather than 36 ~xc5+? ~c7 37
'ii'xdl llexdl 38 f7 l:tld6 0-1 Aseev­
Se.lvanov, St Petersburg Ch 1998,
White should take a draw with 36
'ii'xc5+ 'iita6 37 'ii'c6+ 'iita7 38 'it'c7+
'iita6 39 'ii'c6+.
20 ... dxc3
Black is forced to accept the sacrifice.
21 iidS+ 'iitb6
21...~c8?! occurred in S.Pedersen­
Se.lvanov, Cappelle la Grande 1996. I
had confidently lashed out 20 lLlc3!?
and only spent a couple of minutes.
My opponent now had a long think
and came up with this. I was pretty sure
that I had already refuted it, but having
calmed down I soon realized that there
was not actually a forced win but that
I had t() content myself with 'just' a