Captain Vincent Kompany will also not be risked after missing six games with calf problems.
Mancini hopes both players will be fit to return for the trip to Everton next week.
Mancini: "I don't think it is serious but in this moment we can't take a risk with Sergio.
"Vinnie was training with the team yesterday but I don't think we can risk Vinnie. Maybe he is ready for the next game against Everton."