<I would seriously like to see this line busted for White.>

Good luck with that. :-)

Seriously, though, for reasons you've pointed out elsewhere c5 is generally a bad idea in these kinds of positions. But ...a6 alters the situation, kind of like the position after 1. e4 e6 2. d4 d5 3. e5 c5 4. c3 Qb6 5. Nf3 Nc6 6. a3. 6....c4, usually a bad idea in the French, makes sense here.

after ...a6 the move c5 is known as one of two methodes to fight for white advantage. The other is cxd5.

In any case modern grandmaster don't care any longer about the "prohibition" of c5. As long as there is a tempo win (for example if a back Queen is on b6) or if there are other structural reasons for this move (as here).

1.c4 c6 2.d4 d5 3.Nf3 Nf6 4.Nc3 a6 5.c5 Bf5 6.Nh4< Quite a rare move.> 6...Bg6 7.Bf4 Nbd7< Think this must be new, There is a game with 7...e6> 8.Nxg6 hxg6 9.h3 b6 10.cxb6 Qxb6 11.Rb1 e6 <11...e5 looks possible, but on further inspection leaves black's pawns weak. [11...e5 12.dxe5 Ng4 13.e3 Ngxe5 and black has 3 pawn islands which become objects of attack.]> 12.e3 c5 13.a3 Bd6< With the obvious threat of 14...Bxf4 15 exf4 cxd4 >14.Na4 Qc7 15.Bxd6 Qxd6 16.Nxc5 Nxc5 17.dxc5 Qxc5 18.Qa4+ Ke7 19.Bd3 a5 20.Ke2 Rhc8 21.Rhc1 Qxc1 22.Rxc1 Rxc1 23.b4 Kf8< My Fritz doesn't like this. A good active plan for black seems to be doubling rooks on the 'c' file, playing ...e5 ...e4 and rerouting the knight via e8-d6., and not getting too paranoid about the 'a' pawn. Wang does decide to get paranoid and plays to put his rooks infront of the pawn. This is a negative plan which can only lead to whites initiative. Wang should of been more bold and used his king to support the center pawns if needed, instead of retreating it out of the action. [23...e5 24.Qb5 Rac8 25.bxa5 e4 26.Bb1 R1c5 27.Qb4 Ne8 28.a6 Nd6 and black has chances for counterplay]> 24.bxa5 Kg8< This run away and hide tactic can't be correct, can it?> 25.a6 Rc7 26.Qf4 Rca7 <This is the big question for me. Is this paranoia about the 'a' pawn justified, or should Wang be creating some play of his own. Ok, Carlsen has to prove he can make progress here, but it does seem Wang has set himself up for the slaughter.> 27.Qd4 Ne4 28.Qb6 e5?!< It's inevitable black will lose one of his center pawns after this, BUT it is still a tough job for white to win. If black just stands his ground and plays basic defensive moves, it does seem extremely difficult for white to make much progress. I can't find a clear cut win. Although Rybka on a mega processor might. [28...Nf6 29.Bb5 Nd7 30.Qd6 Nb8 31.Qd8+ Kh7 32.Qb6 Kg8 33.a4 Nd7 34.Qd4 Nb8 35.a5 Rc7 36.Qb6 Rca7 37.f3 Nd7 38.Qd4 Rc7 39.e4 Nf6 40.Qb6 Rca7 41.Kd3 dxe4+ 42.fxe4 Nd7 43.Qd6 Rc8 44.Kd4 I don't know how white makes progress] >29.Ke1 Ng5 30.Bb5 Ne6 31.a4 d4 32.a5 Rc7??< Black still had a lot of fight left until he played this. Credit to Carlsen though who got the type of position which puts the opponent under pressure, and when under pressure you are the one most likely to make the final big mistake. [32...dxe3 33.fxe3 Nf8 34.Qd6 Rc8 35.Qxe5 Ne636.Qd6 36...Nc5 and white is still finding it tough to make any kind of breakthrough.]> 33.Bc6 1-0

Lot's of questions in this game about whether Wang should have taken the passive defensive role after the queen for rooks trade. The way Wang chose was that he would always be defending, and under pressure not to make a losing move.

Before 32,,,Rc7?? it seems his position was still defendable in a practical sense, but being under pressure constantly does crazy things to the mind. It did prove correct - Wang's mind went crazy!

As I've said, great credit to Carlsen who is relentless in his attack. He keeps squeezing you until you 'blackout' - and that's what happened to Wang.

Pillsbury vs Tarrasch, 1895

But of course Tarrasch lost (40 moves later!) by a tempo, more or less, after mistakes and brilliancy by both sides. Here's an example of ...c5-c4 "working" from the same tournament.

I suppose you mean 35.Bc6 - yes, that's a nice idea, I think it works. After 32...dxe3 33.fxe3 Nf8 34.Qb7, Black's best attempt to try and defend against Bc6 seems to be 34...Ne6, so that after 35.Bc6 Rxa6 36.Qxa8+ Rxa8 37.Bxa8 he can play 37...Nc7; but I think White is still winning, e.g. 38.Bb7 Nb5 39.Kd2 Kf8 40.Kd3 Ke7 41.Bd5! (41.Kc4? Nd6+ 42.Kd5 Nxb7 43.a6 Nd6 44.a7 Nc8 45.a8=Q Nb6+; or 44.Kc6 Nc8) 41...Nc7 (41...Kd6 42.Bxf7) 42.Kc4 etc.

I'll tell you something my friend, I think you're on to something there!!

That may be a nice find of yours. Early indications are that there is no defence to that (34 Qb7). White just gives up his queen for the 2 rooks and marches forward with his king.

Why not 32...dxe3 33. fxe3 Nd8. ?

Now the knight covers the c6 and b7 squares. If white tries to get on the a8-h1 diagonal by repositioning the bishop, black should have enough time to reposition the rooks.>