1) Javier Mascherano is the glue that hold Los Albiceleste together.
The captain without the armband. While Messi leads by doing, Masch is the motivational voice. He could be seen pepping the team at half time and he motivated Romero during penalties. Despite taking a knock to his head, and looking suspiciously concussed in the following moments, he got stuck in the game. He dictated the midfield, provided attacking opportunities for Argentina, and dealt with Robben ever so efficiently. His pin point tackle on said Robben in the penalty are in the dying moments of extra time kept Argentina in the game. Man of the Match for me, for sure.
2) Romero is not useless.