In round 3 four of the six games were drawn, and in round 4 it was five of six. The two wins in round 3 saw two of the tailenders lose, both with Black: Varuzhan Akobian to Sam Shankland, and Aleks Lenderman to Alexander Onischuk. Atop the standings it was all draws: Wesley So and Fabiano Caruana drew a 92-mover that never got out of control for either player, while Ray Robson did have some difficulties before securing a draw against Jeffery Xiong.
That left So, Caruana, and Robson tied for first with 2.5/3, half a point ahead of Hikaru Nakamura, who was unable to defeat bottom seed Akshat Chandra with the white pieces - Chandra simply played very well. The sixth game of the round was a short draw between Alexander Shabalov and Gata Kamsky.
Round 4 was a drawfest. Shankland-So was a very easy hold for So, and Robson also had no trouble against Akobian thanks to good preparation. Or at least, no trouble until near the end. Robson wanted to push a bit and rejected a repetition, but maybe 35.Nxa6 Rxa3 36.Nc5 Rf3 37.Nd7!! (hoping to play Be4-c6xb5) would give some winning chances. (The knight is immune on account of 38.Bh7+ followed by 39.g8Q#.)
Onischuk defanged Kamsky's London System for a quick draw, and Lenderman-Xiong also barely made it past move 30. Chandra-Shabalov had a good deal more fight in it, and Chandra was pressing throughout.
The game of the round, and the game of the tournament so far in terms of its importance for the standings, was Caruana-Nakamura. This was one of the oddest Najdorfs I've seen, going 6.f3 e6 7.Be3 h5 (this is more normal in the ...e5 lines, but it's known here too) 8.a4 (this stops ...b5, of course, but White normally plays Qd2, castles queenside, and tries to whip up an attack on the other side of the board) 8...Nc6 (not a normal "Najdorf" move, but with a4 having been played it makes sense here) 9.Bc4 (a new move in an already rare position), and on it went from there. It's hard to assess such a non-standard variation, but it seems that things only got out of hand for Nakamura after he played 21...Kb8 and more especially 24...Qb4. At one time Caruana had a terrible record with White against the Najdorf Sicilian, and maybe that was part of what motivated Nakamura to give it a shot. If so, it was a misassessment: Caruana seemed very at home in the complications, winning quickly and relatively easily.
With the win, Caruana moved into clear first in the tournament with 3.5/4, and also moved into second on the live rating list, passing Vladimir Kramnik's 2801 with his 2805.3. Robson and So are half a point behind going into round 5, the last round before the rest day. Here are the pairings:
- Shabalov (1.5) - Caruana (3.5)
- So (3) - Akobian (1)
- Robson (3) - Lenderman (1)
- Nakamura (2) - Shankland (2.5)
- Xiong (2) - Kamsky (1.5)
- Onischuk (2) - Chandra (1)