user2001: In game 1 of the World Championship 2014 between Carlsen and Anand, Anand chose 12.gxf3. Why not play 12.Qc3+ instead? It takes control over the a1-h8 diagonal and prevents the black Nc6 to jump to d4 or e5. In addition, it gives white the option to grab on f3 with the queen, keeping the pawn structure on the kingside intact.
[FEN ""]
[Event "WCh 2014"]
[Site "Sochi RUS"]
[Date "2014.11.08"]
[Round "1"]
[White "Anand, Viswanathan"]
[Black "Carlsen, Magnus"]
[Result "1/2-1/2"]
[Eventdate "2014.11.08"]

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Bd2 Bg7 6.e4 Nxc3 7.Bxc3 O-O 8.Qd2 Nc6 9.Nf3 Bg4 10.d5 Bxf3 11.Bxg7 Kxg7 12.Qc3+


user4196:            [FEN ""]
                [Event "WCh 2014"]
                [Site "Sochi RUS"]
                [Date "2014.11.08"]
                [Round "1"]
                [White "Anand, Viswanathan"]
                [Black "Carlsen, Magnus"]
                [Result "1/2-1/2"]
                [Eventdate "2014.11.08"]
            
                1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Bd2 Bg7 6.e4 Nxc3 7.Bxc3 O-O 8.Qd2 Nc6 9.Nf3 Bg4 10.d5 Bxf3 11.Bxg7 Kxg7 12.Qc3+ e5 (13.dxc6 Be4 14. Qe5 f6 15. Qc3 Re8 16. Be2 Bxc6)
    (13.gxf3 Nd4 )     
   (13.Qxf3 Nd4 ) 
   (13.dxe6 Qf6 14. Qxf6 Kxf6 15. gxf3 fxe6) 

Computer Houdini 1.5a w32 suggests 13... e5
Now four options for white 13.dc 13.de ep, 13.gf or 13.Qf3 anything else loses a piece.

After 13. dc black replies 13... Be4 and white cannot take pawn on e5. If 14. Qe5 then 14... f6 15. Qc3 (15 Qe4 loses a queen). 15... Re8 this forces white reply  16. Be2 and black just takes on c6 16.... Bc6 , this is a win for black.

13.gxf6 black moves its knight to the centre 13... Nd4 Knight on d4 cannot be moved. Pawn on f3 is weak. Black is better.

13.Qf3 Again same idea – black’s knight occupies the centre Nd4 and whatever white answer is black threatens to crush the white centre 14... c6. Again black is better (maybe not as good as after 13. gf)

13.dxe6 e.p. black needs to cover the diagonal – 13... Qf6 or 13... Qd4 anything else consolidates white’s position in the centre.
13...Qf6 14 Qf6 (otherwise black takes on c3) 14... Kf6 (forced) 15 gf (forced) 15... fe again black is better (weakness on f3)
13...Qd4 white cannot take on d4, so 14. e7 (if 14. gf black takes on c3 and again weakness on f3 is giving black an advantage)  14... Re8 15. gf again cannot take on d4. And now either 15...Re7 or 15... Qc3 and black has better pawn structure.



2001: <p>In game 1 of the World Championship 2014 between Carlsen and Anand, Anand chose 12.gxf3. Why not play 12.Qc3+ instead? It takes control over the a1-h8 diagonal and prevents the black Nc6 to jump to d4 or e5. In addition, it gives white the option to grab on f3 with the queen, keeping the pawn structure on the kingside intact.</p>

<pre><code>[FEN ""]
[Event "WCh 2014"]
[Site "Sochi RUS"]
[Date "2014.11.08"]
[Round "1"]
[White "Anand, Viswanathan"]
[Black "Carlsen, Magnus"]
[Result "1/2-1/2"]
[Eventdate "2014.11.08"]

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Bd2 Bg7 6.e4 Nxc3 7.Bxc3 O-O 8.Qd2 Nc6 9.Nf3 Bg4 10.d5 Bxf3 11.Bxg7 Kxg7 12.Qc3+
</code></pre>
 4196: <pre><code>           [FEN &quot;&quot;]
                [Event &quot;WCh 2014&quot;]
                [Site &quot;Sochi RUS&quot;]
                [Date &quot;2014.11.08&quot;]
                [Round &quot;1&quot;]
                [White &quot;Anand, Viswanathan&quot;]
                [Black &quot;Carlsen, Magnus&quot;]
                [Result &quot;1/2-1/2&quot;]
                [Eventdate &quot;2014.11.08&quot;]
            
                1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Bd2 Bg7 6.e4 Nxc3 7.Bxc3 O-O 8.Qd2 Nc6 9.Nf3 Bg4 10.d5 Bxf3 11.Bxg7 Kxg7 12.Qc3+ e5 (13.dxc6 Be4 14. Qe5 f6 15. Qc3 Re8 16. Be2 Bxc6)
    (13.gxf3 Nd4 )     
   (13.Qxf3 Nd4 ) 
   (13.dxe6 Qf6 14. Qxf6 Kxf6 15. gxf3 fxe6) 
</code></pre>
<p>Computer Houdini 1.5a w32 suggests 13... e5</p>
<p>Now four options for white 13.dc 13.de ep, 13.gf or 13.Qf3 anything else loses a piece.</p>
<ul>
<li><p>After 13. dc black replies 13... Be4 and white cannot take pawn on e5. If 14. Qe5 then 14... f6 15. Qc3 (15 Qe4 loses a queen). 15... Re8 this forces white reply  16. Be2 and black just takes on c6 16.... Bc6 , this is a win for black.</p>
</li>
<li><p>13.gxf6 black moves its knight to the centre 13... Nd4 Knight on d4 cannot be moved. Pawn on f3 is weak. Black is better.</p>
</li>
<li><p>13.Qf3 Again same idea – black’s knight occupies the centre Nd4 and whatever white answer is black threatens to crush the white centre 14... c6. Again black is better (maybe not as good as after 13. gf)</p>
</li>
<li><p>13.dxe6 e.p. black needs to cover the diagonal – 13... Qf6 or 13... Qd4 anything else consolidates white’s position in the centre.<br />
13...Qf6 14 Qf6 (otherwise black takes on c3) 14... Kf6 (forced) 15 gf (forced) 15... fe again black is better (weakness on f3)<br />
13...Qd4 white cannot take on d4, so 14. e7 (if 14. gf black takes on c3 and again weakness on f3 is giving black an advantage)  14... Re8 15. gf again cannot take on d4. And now either 15...Re7 or 15... Qc3 and black has better pawn structure.</p>
</li>
</ul>
