Aguero picked up a knock against Manchester United last weekend, and while Pellegrini has insisted that it's not a major issue, the former Malaga boss has revealed that the Argentinean will miss the trip to Villa Park.
The 60-year-old told reporters: "Aguero finished the last derby in the last play with a small pain.
"I think that it was nothing important, but I think that it was a risk for him to play three games in the same week.
"We will leave him for next Wednesday, but he will be absolutely fine."
Aguero scored twice in the 4-1 derby victory over their city rivals.