The game had two crucial moments. Trying to generate winning chances, Nakamura challenged the a1-h8 diagonal by 22…Be5!? This allowed a discovery on the undefended Bishop by 23.Nf5+, but Hikaru had calculated that it was safe for him to move out of check and defend the Bishop by 23…Kf6, even though this walks the monarch out to the center and hangs a K-side pawn. White went back 24.Nd4, and the players repeated moves 24…Ke7 25.Nf5+ Kf6 26.Nd4. Hikaru could have claimed a draw, or tried the double-edged 26…Nc3!?, but went to the discovery well once too often by 26…Kg6? allowing 27.Nxe6! Evidently he miscalculated something in the resulting tactics.
Indeed, there is an amazing temptation in those tactics. The main line in the capturing melee appears to be 27…Bxa1 28.Nxd8 Rxd8 29.Bxd5 Rxd5 (protecting the N on c5) 30.Rxa1 Ba6+. Now the natural 31.Nc4 is met by the incredible 31…Nxb3!! 32.axb3 Bxc4+ 33.bxc4 (33.Ke1 stays alive) Rxd1+ 34.Rxd1 b3 with two passers on the 6th against the Rook. But alas White has 31.Kg1! and after 31…Be2 32.Rdc1 Rxd2, the N on c5 is no longer protected!
So I would bet that Nakamura was tempted by the brilliancy and overlooked that his Knight on c5 would be unprotected. We’ve all done that…
What’s wrong with Nakamura?
The game had two crucial moments. Trying to generate winning chances, Nakamura challenged the a1-h8 diagonal by 22…Be5!? This allowed a discovery on the undefended Bishop by 23.Nf5+, but Hikaru had calculated that it was safe for him to move out of check and defend the Bishop by 23…Kf6, even though this walks the monarch out to the center and hangs a K-side pawn. White went back 24.Nd4, and the players repeated moves 24…Ke7 25.Nf5+ Kf6 26.Nd4. Hikaru could have claimed a draw, or tried the double-edged 26…Nc3!?, but went to the discovery well once too often by 26…Kg6? allowing 27.Nxe6! Evidently he miscalculated something in the resulting tactics.
Indeed, there is an amazing temptation in those tactics. The main line in the capturing melee appears to be 27…Bxa1 28.Nxd8 Rxd8 29.Bxd5 Rxd5 (protecting the N on c5) 30.Rxa1 Ba6+. Now the natural 31.Nc4 is met by the incredible 31…Nxb3!! 32.axb3 Bxc4+ 33.bxc4 (33.Ke1 stays alive) Rxd1+ 34.Rxd1 b3 with two passers on the 6th against the Rook. But alas White has 31.Kg1! and after 31…Be2 32.Rdc1 Rxd2, the N on c5 is no longer protected!
So I would bet that Nakamura was tempted by the brilliancy and overlooked that his Knight on c5 would be unprotected. We’ve all done that…