First organizing mistake

Yesterday's derby between Mexico and Uruguay went pretty well, was very entertaining with four goals scored out of which one was a real beauty, powerful strike. But before that we had a little mix up with the national anthems.
Instead of Uruguay's Chilean anthem was played in the ceremony before the beginning of the match. Most of the players were astonished and bewildered who did not know what to do and how to approach. After the game Copa America officials have apologized to Uruguay blaming it on a 'human error'.
Maybe that is why Alvaro Pereira was that nervous as this blunder definitely affected him opening the score in the third minute as the Mexicans forced him to make a mistake.