One of the best brazilian player of the tournament, no doubt. His game against Croatia wasn't great though (like most of his teamates) but it's mostly because of Paqueta's terrible game. Tite made a very bad call and Casemiro was left alone with a close to impossible task.
His defending in the play when Brazil concedes a goal is very bad though, chasing players without any influence instead of covering the center of the pitch, he left Marquinhos with 2 players to guard. Oviously, he isn't the only one responsible