Hikaru Nakamura has enjoyed a very good career score against Fabiano Caruana, and although Caruana made up some ground by beating Nakamura in St. Louis last year Nakamura struck back today against his countryman. It was a strange win, however, as Caruana was doing just fine and had reached an equal rook ending that seemed headed for a reasonably quick and straightforward draw. Near the end of the first time control, things got out of hand for the Italian-American (and in favor of the American who spends more time in Italy thanks to his Italian girlfriend) when he hit upon the dubious 38...b5 and the outright terrible 40...g5. Both moves weakened Black's structure, and the latter also invited White's rook in to cause lethal damage.
That put Nakamura at 2.5/3 (and to #2 in the live ratings), the same score enjoyed by Veselin Topalov (now the world's #3). Topalov won with great ease against Maxime Vachier-Lagrave on the black side of a Meran Semi-Slav, thanks to MVL's choosing a mistaken tactical idea starting with 20.Bd2. That move may not have been so bad in itself, but the plan to go for Nd5 and Ba5 failed completely. Two moves later, Black was winning, and White resigned after a further six moves were played.
The remaining games were drawn, and that left Anish Giri alone in third place with 2/3. He was completely lost to Magnus Carlsen, whose lucklessness against Giri is a source of endless mirth to the young Dutchman. The only positive for Carlsen is that it wasn't a third straight loss.
Levon Aronian was very happy with his position out of the opening against Jon Ludwig Hammer, but to his dismay Hammer played very well after that and managed to hold the game, with some effort. Some, but especially after 34.Re4 h5!, it wasn't too tough to save the game. White's rook was stuck for the rest of the game.
Finally, Viswanathan Anand enjoyed an advantage against Alexander Grischuk much of the way, but didn't manage to convert it into anything substantial. Anand has been getting good positions, but his opponents have been slipping away.
Tournament site here, games here (but without notes today).
Here are the round 4 pairings: