The rest day may have been just what Magnus Carlsen needed, as he commenced the second cycle of the Vugar Gashimov Memorial by defeating Shakhriyar Mamedyarov for the second time in the tournament. This broke his two-game losing streak and brought him into shared first with Teimour Radjabov after the latter drew against Sergey Karjakin. (Fabiano Caruana and Hikaru Nakamura also drew their game.)
The Mamedyarov-Carlsen game was complicated and there were all sorts of differing opinions on what was going on. Mamedyarov's 5.Nf3 (after 4.Qc2 d5 in the Nimzo-Indian) was very rare and a surprise to Carlsen. Jan Gustafsson was entirely unimpressed by this idea commentating on chess24 and thought Carlsen was better throughout; the only question was how much. Mamedyarov was very happy with his position up until he played 22.f5; that was inaccurate and his few succeeding moves included even more serious errors. He correctly felt that 22.Re1 would have been better, but if I understood him correctly he seemed to think he would have had the better chances then. And then there's Houdini, which agrees in part and disagrees in part with both Gustafsson and Mamedyarov. It evaluates the position in the short-term aftermath of 5.Nf3 as at least very slightly better for White, but soon enough Carlsen obtains an edge - one he would have kept even after the better 22.Re1.
To interject based on my own study and experience (admittedly and obviously at a considerably lower level than Carlsen's and Mamedyarov's) I would say that positions where Black plays ...dxc4 and holds the extra pawn while White gets a d4 + e4 pawn center in return are some of the hardest to play in all of chess. They come up in various Slavs, Semi-Slavs, Triangle Systems and even, as here, in openings like the Nimzo-Indian. I even noticed that there were some openings where I handled the structure and the resulting positions pretty well, while there were others where I was relatively clueless. So I'm at least not so surprised by the differences of opinion, and I won't even go so far as to say that Houdini's evaluation was correct. I think the line needs more tests before stable evaluations can be offered.
On to tomorrow's round. Here are the round 7 Pairings, with player scores in parentheses: