| YouRang: Carlsen (black) really pulled at rabbit out of the hat in this game. I think white erred by letting black get his pawn all the way to d2 in moves 86-89 (e.g. he should have played 86.d2 instead of 86.Bd7). However, that's not what lost the game, it just meant that white would have little room for error. The critical position was here (white's 90th move):
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The one thing that is clear in this position is that white cannot allow that knight to come to e4. That means his bishop must remain on the b1-h7 diagonal, and thus his only moves are 90.Ke2 (the B prevents ...Kc2), or moving the bishop to b1, c2, or g6. Inexplicably, white played <90.Be6??>, leaving e4 open. I imagine that Carlsen practically jumped: <90...Nd4> threatening ...Nxf2+ <91.Ke2> (other moves are no better) <91...Nxf2>. I think Carlsen would have wrapped things up quicker with 91.Kc2, but he opts to win a pawn and protect his Pg4 while threatening ...d1=Q. [diagram]
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<92.Bb3!? Kxb3> (again, other moves might have been less work, like 92...d1=Q! 93.Bxd1 Nxd1 94.Kxd1 Kd3!  ) <93.Kxd2 Kc4 94.Ke3 Nh3!> [diagram]
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See how nicely, the N defends the Pg4 by preventing access to f4 <95.Ke4 Kc3 96.Ke3 Kc4 97.Ke4 Kc5 98.Ke5 Nf2! 99.Kf4 Kd4!> [diagram]
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Another pretty position as the pawn black pawn is guarded by the knight, but the knight is also in a sense guarded by the pawn since it cuts off f3. The white king must back off to f5 (or g5) and the black king moves in to finish off the remainging pawn and win. | 
