Raheem Sterling can equal Sergio Aguero, Yaya Toure - Manuel Pellegrini

MANCHESTER -- Manuel Pellegrini declared his confidence that Raheem Sterling can reach the levels of Sergio Aguero and Yaya Toure as the £49 million man prepares to face his former club Liverpool for the first time.

Sterling rejected a new contract at Anfield and the acrimony surrounding his July transfer means he is likely to be jeered by Liverpool fans at the Etihad Stadium on Saturday.

But Pellegrini said it would be a "special" day for both Sterling and James Milner, who moved in the opposite direction, as he tipped Sterling to progress further.

The Chilean stressed that the 20-year-old remains a work in progress but believes he has the potential to scale the heights in the way four-time African Footballer of the Year Toure and Aguero, whom Pellegrini has described as being the third best player in the world, have done.

"Yes, yes," he said in a news conference. "It depends on the way he improves but the important thing is he is just 20 years old. He has a lot of years to work. He will be a very important player, not only for Manchester City but also for England."

"I always say that Raheem is a very young player. He must improve a lot and in important things. It is important also he can demonstrate in every game but I am very happy with the way he is playing. He is an important player and will be more important in the future."

Sterling has scored six goals in 15 games for City so far but has never lined up against Liverpool before.

"I always think it is special for the player to play against [their old club]," said Pellegrini. "Not only for Raheem, but all the players to play against the team they worked for. Maybe it will be exactly the same for James Milner but those situations are part of the career of the player. They are now defending another shirt."