It was a great day for the Azeri players at the Vugar Gashimov Memorial: Teimour Radjabov defeated one leader, Magnus Carlsen (who also happens to be the world champion and world #1), while Shakhriyar Mamedyarov defeated Fabiano Caruana, the other leader. After five rounds, the first cycle is complete. Radjabov is at +1 and in clear first, Mamedyarov is -1 and alone in the cellar, and Carlsen, Caruana, Nakamura and Karjakin (the latter two drew today) are all on 50%.
Radjabov is a great King's Indian specialist, and simply did a better job of understanding and assessing the goings-on than his illustrious opponent. Carlsen was unhappy about his 19th move (19.exf5) and confessed that he was wrongly optimistic about his exchange sac. He thought that Radjabov would be without play, but when 28...b5 came it was clear that he was mistaken. Radjabov finished very effectively and was a deserved winner.
For Caruana it was a different story. Mamedyarov was better forever, but Caruana was holding down the fort pretty successfully. The critical moment came at the start of the third and final time control, when Mamedyarov played 61.e4. Black had a choice, to force the trade of queens with 61...Qg6 or to force matters with 61...Qc3. Caruana thought for half an hour and made the right decision from a computer perspective, but from a human point of view it was at least questionable. The former would have led to further suffering, but the position would have been easier to play, much more manageable. Instead, he played 61...Qc3. This draws if one sees everything - the computer gives it a shiny 0.00 evaluation - but Black must find a lot of only moves. When Caruana missed one of them - 67...Qf3! - it wasn't just some sort of inaccuracy. Black was completely lost, and Mamedyarov successfully converted his advantage.
Tomorrow is a rest day, and on Saturday the second cycle begins with these pairings: