The Premier League encounter at 13.30 on Sunday is already being billed as a huge game in the title race and the Spanish international would be a big miss for City.
Silva also misses tonight’s Champions League fixture against Borussia Dortmund in the Champions League, suffering from a hamstring injury.
Mancini told the Daily Mail “Silva is not here because he has a hamstring injury, and we do not know at the moment if he can recover in time for the derby,’ ‘We will try, but we will have to see.”
The Manchester City boss did insist though that tonight’s fixture was important too with a place at the Europa League at stake.
He added “‘We want to qualify for the Europa League, and all the players who are fit and available are here with us. We have several injuries, but those who were fit to travel are ready to do everything they can to win the game.
“It will be difficult, because Borussia Dortmund are one of the best teams in Europe, but we will do our best to avoid dropping out altogether.
“It could be difficult for us if we manage it, because in the Europa League, you play Thursday and do not have much time to recover for the Premier League. But we need to reach the Europa League if we can, and we will be doing our best.”