Argentina have not been at their best so far in Brazil, but have reached the last 16 with a game to spare thanks to narrow 2-1 and 1-0 wins over Bosnia-Herzegovina and Iran.
Their victory over Iran proved particularly difficult, as Carlos Queiroz's dogged side defended resolutely before being undone by a moment of injury-time brilliance from Lionel Messi.
And even though he is thrilled to have picked up maximum points from their two games so far, Di Maria believes Argentina need to raise their game if they are to stand any chance of landing a third World Cup.
"The important thing for us was to win," said the Real Madrid man.
"There are seven games that you have to give everything to win (to win the tournament).
"It is difficult to play against a team that gets far behind the ball. Iran played a good game, but at times it was difficult.
"We are satisfied because we won (but) there are things to correct and improve."
