It was not a good day for the favorites in the U.S. Championship, with the top three seeds scoring a grand total of half a point between them. The leader, Hikaru Nakamura, came out of the opening against Sam Shankland, but it wasn't long before it had disappeared and Shankland had the edge. Periodically the evaluation would revert to equality and then back again in Shankland's favor, and in fact when the draw was agreed Shankland again had a slight edge.
Thanks to the draw Nakamura remains in clear first with 4.5/6, half a point ahead of Ray Robson. Robson leapfrogged Wesley So, whom he defeated in a see-saw game. Robson was better for most of the first 25 moves, but when the game sharpened So outplayed him in the complications and was apparently on his way to a win. So had a great opportunity on move 25 with the double sacrifice 31...Rxb7! 32.Qxb7 Bd5 33.Qc7 Bxg2! The bishop can't be taken, but if it's not then it will play a major role in what should be a decisive attack on White's king. Even after missing that chance Black was better, but errors on moves 34-36 gave Robson a winning advantage he converted a few moves later.
Meanwhile, no sooner had Gata Kamsky made his way into the chase with a win in round 5, his first victory of the tournament, did he fall back to the pack by losing in round 6. Kamsky played a Chebanenko Slav against Alexander Onischuk, quickly surrendering his "bad" light-squared bishop to achieve a solid, Fort Knox-like position without any bad pieces. Unfortunately for Kamsky, Onischuk did a very nice job of making his bishop pair count, opening the board and saddling Black with pawn weaknesses. The nature of White's advantage kept changing, but the fact of that advantage was a constant. Most of the time it was substantial in magnitude. Although Kamsky put up a lot of resistance, Onischuk was finally able to break him down and grind out the win in 88 moves.
Onischuk now has 3.5 points, and is tied for third with Wesley So and Sam Sevian, who won again today. His opponent, Kayden Troff, was better and even winning for most of the first part of the game, and still wasn't losing until his 47th move. 47.Kg3 was a serious mistake - something like 47.h3 should have been preferred. The point is that after 47...Rd6 48.Rd6 Rxc7 White can play 49.Rxd6 when his king is on f3 but not when it's on g3, as in the latter case there's 49...Rg7+. (In the former case 49...Rf7+ 50.Rf6 is equal.) A technical task remained for Sevian, and he was up to the challenge.
In the other two games, Conrad Holt defeated Varuzhan Akobian in a messy battle, and Timur Gareev and Daniel Naroditsky had a short and safe draw.
In the women's championship the leader, the surprising Katerina Nemcova, managed to extend her lead over Irina Krush to a full point. Nemcova beat Jennifer Yu with the black pieces, while Krush was unable to cash in a winning advantage against Anna Sharevich and only drew. Nemcova has 5/6, a point ahead of Krush and Rusudan Goletiani, who defeated Apurva Virkud with Black. Paikidze and Abrahamyan are a further half a point behind, so at least for now the rating favorite (Krush) is anything but a runaway favorite to pick up her 7th U.S. women's championship title.