csmath: 14. Bc2!
[Crazy move but completely warranted. Bishop is controlling a4 square so that rook can go to c5. He also planned Bb3 with tactics on g6 and f7. Very original and creative play by Aronian.]
After 18 moves it is white that has developed and black has obvious problems with defending king against 4 pieces poised for attack.
19. Re5!?
[Yet another original play by Aronian.]
20. h4!
[Clearly Aronian has no peaceful intentions.]
20. ...Rad8
21. h5!
[No time for withdrawals. 21. Qb4 Bc8 is not the alternative Aronian wants to pursue.]
23. hxg6! Bxf3?!
[I think Nakamura is absolutely amazed by Aronian's audacity so he misses opportunity to exchange queens immediately: 23. ...Nd7, 24. Ra5 Qxc3, 25. bxc3 Bxf3, 26. gxf3 fxg6 looks like more pleasant defensive alternative with complex ending.]
26. gxf7?!
[26. Rd1 fxg6, 27. Qd4 looks stronger as white queen threatens a7 rank after f4 while d4 pawn is goner either way. Black queen cannot remove itself from the bind.]
26. ...d4?!
[Another imprecision and missed opportunity. Alternative: 26. ...Kxf7, 27. Qc7 Kg8, 28. Re7 Rc8!, 29. Qe5 Qxe5. 30. Rxe5 Rc2 and black has good chances for a draw due to activity of his rook on second rank.]
Nakamura loses pawn with some chances in the ending but ...
40. ...Rh8?
[40. Kxd5 Rxh4, 41. Re2 would be lost without pawns on the queenside but with them it is more resilient. Nevertheless I would consider this close to lost. Nakamura's move makes it sure.]
41. ...Re8?!
[The position is already lost anyway.
41. ...Rg8, 42. Kf5 Rg1, 43. Rxh4 b5, 44. f7! Ke7, 45. Rh7! and black loses queenside pawns or d/f promotes.]
42. Rxh4
with king and rook ideally placed for promotion of f-pawn while black rook and king are completely disharmonious.
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Nakamura fancies himself as a challenger to Carlsen. Do you think this endgame would stand up to Carlsen scrutiny?