Both teams remained goal less at half time.
After a lacklustre first half, Atletico's forward Luis Felippe Goncalves Soaresdrew the first blood by pushing into the goal a shot from the left flank in the59th minute.
Two minutes later, forward Joao Pedro Heinen Silva struck home the second for Atletico.
In tomorrow's Group-B match, Argentina U-23 will face Germany's TSV 1860 Munchen club.