Aguero, who is City's top scorer with 19 goals this season, has been out since suffering a calf injury in the 6-3 defeat of Arsenal on 14 December.
While Sunday's trip to Newcastle will come too soon, the Argentina international is back in training and is in line to feature against Cardiff next Saturday.
"Aguero continues working and maybe next week he can be fit," Pellegrini confirmed at his pre-match press conference on Friday.
City have won six of their seven games in Aguero's absence - the exception being a 1-1 draw at Blackburn in the FA Cup third round - but his return will be welcomed ahead of next month's Champions League date with Barcelona.
Pellegrini expects to have Yaya Toure available on Tyneside after the midfielder picked up a knock in the midweek Capital One Cup rout of West Ham.
Pellegrini said: "Yaya is okay. There was a little pain in his ankle but nothing important."