"I think Medel is crucial in defence and Valdivia is aplayer who can create things in midfield," Aguero told a news conference ahead of Saturday's final between the two sides.
"Vargas is on form and can create a goal out of nothing at any moment. He's a player who maybe doesn't get that many touches of the ball but he's always there so you have to be careful.
"Chile have some great players ... they have a great team," added the Manchester City marksman.
Medel may hold the key as Chile try to stop Aguero and attacking partner Lionel Messi.
Valdivia has been the host nation's most inventive midfielder in the tournament while Vargas has scored four of their 13 goals including a double in the 2-1 defeat of Peru in the semi-finals.
Aguero has bagged three of Argentina's 10 goals and is their top scorer in the competition.
(Editing by Tony Jimenez)
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