Willempie,

I'm sure 10....Nb6 is just bad.  White has the obvious 11.Nxc6 Bxe3 12.Nxd8 Bxd2+ 13.Rxd2 Rxd8 and White's pieces are much better placed than Black's.  White probably has even better, possibly with 11.g4.   I'd have to check it more thoroughly, but I suspect there are excellent reasons why I haven't seen it recommended in any of the literature.

Bad, 

Thanks for adding the supplemental lines! (In the 10...Qa5 lines, I typed 12.Bxe3 when I meant 12.Qxe3 of course.  But I agree with your assessment.)

MarinFan, 

I find it fascinating that old books say that a move is questionable, such as 10...Qe7 and then we see someone like Bareev play it without any noticeable improvement in mind.  I'd like to see Khalifman's analysis of 10...Qe7 to see what justification he gives for it.

Interesting - thanks for info Mr. Pritt. I was a bit shocked to learn Khalifman had rcommended this Nb3 line, but I remember years ago when I studied this line as Black it was an annoying move I didnt fancy playing against, not sure why it never really caught on - apart from Dutch GM Nijboer who is a bit of a specialist in it.

I have a feeling Anand v Morovevich was played after the book was sent to print (could be wrong -somebody please confirm or correct!) - but I suspect Anand had an original draft of the analysis since he decided to vary from his standard stuff and play Nb3 in San Luis.

I'd prefer 10..Bb4 to correct the black mistake on move 3

Seriously I would give a thought to what to do with Nd7, it is completely in the way atm, but eg 10..Nb6 may be tempting fate on the kingside. So maybe playing for a quick f6 is best.

I haven't done any data searches.  I was just looking at the position trying to come up with alternatives to the moves I listed.   

The only one I keep returning to is 10...Qa5?!  If 11.Nb3 Bxe3 12.Na5 Bd2+ 13.Rd2 Na5 14.g4 looks ok for White.

Also, 12.Bxe3 Qc7 accomplishes precious little for Black.  Does anyone know if there's a theoretical assessment for 10...Qa5?

Ostap, 

This will be fun!  We're going down theoretical lanes today.

I'm going to wait about 24 hours before responding to see what my allies have to say.

My main choices are: 

• 10...Nxd4
• 10...Bxd4
• 10...a6
• 10...Qe7
• 10...Something else.  (Please explain what that may be!)

Again, thanks for your help!

Haven't looked at this as much I expected to have by now (minor distractions elsewhere http://www.chesspub.com/cgi-bin/yabb2/YaBB.pl?num=1151879306).  Before choosing, I wanted to post a few lines for comparison/discussion, etc.

Well, we're still in theory, and I think it's a choice between 10.g3 and 10.0-0-0, which MNb initially suggested several days ago.

10.0-0-0 seems to please everyone, while 10.g3 has gotten a rather lukewarm reception.  Add to this, the well-known tendencies of one of my chief allies (a diehard Spielmann supporter with a serious Iljin-Zjenevsky addiction), my own love of attacking play (don't really understand anything else - if we reach an level endgame you guys are going to have to carry me! ), then opposite wing castling seems a pretty natural choice (what was that other move again? ).

So, it will be 10.0-0-0 unless someone here strenuously advocates 10.g3 (er, not you Smyslov_Fan ).  I will give anyone who wishes a bit of time to voice their opinion on this, and will make my choice official this evening.