The Serbian defender was sidelined with an ankle injury during pre-season and missed City's opening two Premier League fixtures of the new campaign.
However, Pellegrini has confirmed the 20-year-old is available for selection for the game against Steve Bruce's newly promoted outfit at the Etihad Stadium on Saturday.
Pellegrini has been hit by something of a defensive crisis in the early weeks of the season, with captain Vincent Kompany and defender Micah Richards also sidelined with groin and knee problems respectively.
This meant midfielder Javi Garcia had to fill in at centre-back in last week's defeat at Cardiff City, but the Chilean has been lifted by the news of Nastasic's return, and also offered updates on Kompany and Richards.
"Matija is available to play tomorrow," Pellegrini revealed on Friday. "I think Javi Garcia didn’t do a bad job as he normally plays in midfield.
"But it is Nastasic’s natural position, so of course it is better we have him there.
"Nothing is new with Vincent. (At the time) the doctor said it will be four to six weeks. Maybe next week we will see how he improves, but less than one month is impossible.
"Micah is not available for this game, but I hope that next Monday we will start working normally with him."
