Of that group, Silva is the only one in line for a return in Monday night's game against Wigan Athletic. Mancini has said that he believes only Barcelona could deal with the amount of problems his side have faced with injuries and African Cup of Nations call-ups.
"When I said one month ago that December and January would be the crucial months it was because I know football," said the Italian.
"Every year in every squad you have one difficult moment.
"At the moment we are not strong and we have lost important players, so it is difficult."
City are currently top of the Premier League by goal difference.