Manchester City star Aguero started both of Argentina's first two Group D games as a substitute, before being given 90 minutes in their 3-0 win over Bolivia as they sealed top spot.
But with Napoli forward Gonzalo Higuain - coming off a record goals haul in Serie A this season - preferred up front, Aguero says he is happy to play his part as a substitute at Gillette Stadium in Foxborough.
"You have to try to be happy, because there are many forwards out there who would love to be in this position," the 28-year-old said.
"When I played with Higuain during the [Alejandro] Sabella era, we enjoyed it very much.
"But now I must respect the coach and give my best to those who are given starting spots."
Aguero believes he will be named on the bench for their last-eight clash with Venezuela, but is ready to play his part when needed.
"I don't think I will be in [among the starters], but I don't know how we will line up. Since the Copa started I've been on the bench, and I believe it will continue like this," he said.
"I have to just prepare myself for when the team and coach needs me. But I knew this could happen, because Higuain had a very good season."
Argentina coach Gerardo Martino gave Marcos Rojo (knee) and Nicolas Otamendi (sore throat) a rest from training on Thursday, but the two are expected to be back in defence for Saturday's clash against Venezuela.
Venezuela coach Rafael Dudamel, meanwhile, has a full squad of players to choose from as the nation look to qualify for the Copa semi-finals for just the second time in their history.
The team have enjoyed a resurgence since Dudamel took over in April - with the side sitting last in qualifying for the 2018 World Cup - losing just once in their six games under the 43-year-old.
Salomon Rondon scored the only goal of the game as Venezuela booked their quarter-final spot with a 1-0 win over 15-time champions Uruguay, and the West Brom striker is dreaming big in the United States.
"What's been happening in the World Cup qualifiers stays there," he said. "This Copa is very important for us, and we are here to play all six games.
"This tournament is a great opportunity to do good things, with players who are doing very well at their clubs, and with youngsters who are continuing to grow. This Copa is important to renew Venezuela's image.
"We are convinced and we believe in our ability because we have prepared well, we have an incredible group and even though we are playing a difficult rival, we don't feel like we're below anyone."