vinidivici: This line well known as a sharp line, but actually the results favors to white if you know how to use it, but black with the right defense could achieve draw.
Im no surprised that Jan Timman should be know this line and practice it.
I can say that Timman played the perfect moves for this particular line, so Smeets lost because he made mistakes along the way.
I remember at least Polgar used this line twice and won both of it.
after 12...Nbd7 there are 2 moves 13.Bc4/Bxd4, well you can sweat your head calculating both lines, but what for...the line has been analyzed many time, and that shows 13.Bc4! is better.
You just need take your concerned book, practice it, make it far easier if you use the engine help.
And believe me the line is fun, and not so hard to memorize the characteristics of the line. Sometimes in my 10 or 15 minutes game in the online games, i used this line, and i have a good record of it. But rarely found this on the real tournament matches.
After 13.Bc4, there are some clues to simplify the calculations for white
1. Always ready to sacrifice the black squared bishop (Bxd4), to open e-file and finally white rook would occupy that file.
2.Always ready to sacrifice the white squared bishop (Bxf7), if black takes (Kxf7), then queen check (Qf5+), would such an enormous advantage for white.
3.Just like above, always ready to attack with the queen in the kings side. That doesnt always mean to f5 square and checking the black king but also h3 square, i would give an example beneath.
4.Rook always ready to occupy the e-file.
5.gxf6 suggested in the right moment.
if 13...dxc3 14.Bxf7+ suggested itself 14...Kxf7 15.gxf6 Qxf6 16.Qh5+ Ke7 17.Bg5...1-0 black would lose the queen.
if 13...dxe3...SAME RESPONSE 14.Bxf7+ Kxf7 (now safe because white doesnt have bishop anymore. 15.gxf6 Qxf6 16.Qh5+ Kg8 17.Rhg1+ Bg7...DRAW with the right defense. Imagine in the 13...dxc3 line white still has the bishop so 16...Kg8 doesnt work anymore because 17.Rhg1 Bg7 white has 18.Bh6!!...1-0
Why i say this line is easy to use for white? Because after the first first sacrifice 9...gxf5 10.exf5, black has the obligation NOT to be greedy and taking back the knight eg:10...Nfd7 11.Qh5, now white attack is hard to resist.
and if 10...Ng8 11.Nd5...now white has a very active position, black could achieve draw but he has to be ready to hamper the swift attack from white. eg: 10...Ng8 11.Nd5 Nxf5 (greedy move) 12.Bb6 Qxg5 13.Nc7+...black lost the rook probably the best response is 11...Nd7. But after that white would have Qf3/Ba7/f6 to follow, for the one missing piece, white has the compensation for being very active and its hard to defense by black.
So the key is the first sacrifice by white is a "waxy" sacrifice, because its promising the f6 knight back. If we have that kind of mind frame so, it is easier to think that white wouldnt be have no objection to sacrifice other pieces (bishops) for the sake of mobility.