Hart's error which led to Chelsea's winner in City's 2-1 Barclays Premier League defeat at Stamford Bridge last Sunday was the latest in a series of high-profile blunders he has made for club and country.
He was replaced for Wednesday's Capital One Cup fourth-round tie at Newcastle by Romania Costel Pantilimon, who has become City's regular goalkeeper for domestic cup competitions since joining in 2011 and did well in a 2-0 extra-time win.
It has been reported that Pellegrini has opted to stick with that selection for Saturday's home league clash with Norwich, and if he has it will be Pantilimon's Premier League debut.
Pellegrini gave little away at his pre-match press conference on Friday, but did emphasise that, while he valued the thoughts of City's goalkeeping coach Xabier Mancisidor, the call was ultimately one the manager must take.
Asked if Hart would be returning to the team for the Norwich game, Pellegrini said: ''Tomorrow you will know the answer.
"It is a decision I have to take every week with 22 players.''
And asked how much he relied on Mancisidor telling him about City's goalkeepers, Pellegrini said: "It is an important opinion, but I decide who will play, not him."
Various commentators have had their say on Hart's form, and thoughts on whether dropping him in the league will protect him from the spotlight or further knock his confidence are likely to be key to Pellegrini's decision.
He would not be drawn on how Hart had reacted to being left out of the Newcastle fixture.
''You must ask Joe - I can't answer for him how disappointed he was,'' Pellegrini said.
''All of you, the players and me saw what happened. But he is a football player and every week he is under the same pressure."
He added: ''I am always very careful with all the players, not only Joe.''
Asked more specifically about Pantilimon, Pellegrini said: "Every player in the squad has his right to play and I have to decide every week who will.
"Ask Costel maybe (about whether he feels he has earned his chance). He does not play too often but I always see the players every day.
"I'm always talking with all the players, not only when they are in a bad moment - also when they are in a good moment. It is my duty to do it every week."
What is certain about City's team for the Norwich contest is that it will not feature Stevan Jovetic, out with a calf injury, Javi Garcia, who has an unspecified problem sustained in the Newcastle game, or Vincent Kompany.
City captain Kompany has missed the last four matches due to a thigh problem that forced him off early in the victory over Everton on October 5.
Regarding the Belgium defender, Pellegrini said: ''Vincent is progressing but I think it will be after the international break maybe that he will be fit - before that I think is difficult.
''I think we have a strong squad just for this case. Other players can play.
''In the last five matches, we won four and lost once against Chelsea and I think we deserved more.
''He is always an important player, but we can play also without him.''
City are sitting seventh in the Premier League, and Pellegrini has stressed the 18th-placed Canaries should not be underestimated.
The Chilean said: ''If we think we will win easy, it is a great mistake. The team will be very conscious about that. We must do a very good game.''
Of the pressure created by big-spending City's mixed start to the campaign, which sees them currently six points behind leaders Arsenal after nine league games, Pellegrini - appointed over the summer - said: "It is not more pressure. This team always has the same pressure to win.
"We could be at the top of the table and we would have the same pressure. We are six points behind, but the team is playing the way I want.
"For different reasons we lost important points away but we still have 87 points to fight for so we are just starting. We are sure that the team will be soon at the top of the table."