Aguero is in a rich vein of form, having scored nine times in seven matches, taking his tally to 13 goals for the season.
The Argentine's recent performances saw him win the Barclay's Player of the Month for October and Pellegrini insists the "incredible" Aguero is proving he is one of the best players in the country.
"It is absolutely well deserved," Pellegrini said. "Sergio has had an incredible last month.
"I always thought he was incredible because he is a top player, but now he is in a great moment.
"It is not only Aguero and Negredo - the team is playing very well," he added. "All the midfielders - (David) Silva, (Samir) Nasri, (Yaya) Toure, Fernandinho - are really playing very well.
"The way the team plays I also think benefits both of them."
City go into this weekend's Super Sunday clash full of confidence after scoring 12 goals in their last two games, as well as securing qualification for the Champions league knockout stages for the first time in their history .
Ahead of his first visit to the Stadium of Light as Manchester City manager, Pellegrini says his side will continue to adopt the same approach to every match.
"I think about different things - one is the Premier League, one is Champions League," he said.
"We finished with the Champions League last Tuesday, now we must think about the Premier League.
"But we don't need to change the mind. We are always involved in both competitions exactly the same.
"Normally teams do not play the same way away as at home, it is different, but not in our case."
Pellegrini added: "We are going to Sunderland. They are playing well now with Gustavo Poyet and they will be a difficult team to beat."