City are at Old Trafford tonight.
Mancini said: "No one plays well against United because they only play with fear. Every team that plays against United plays very soft because they think this game is difficult, that they can't beat them. It is not true.
"'If you play strong against United, you can beat them. I don't think they don't play 100 per cent but their mentality is poor in those games against United. They think they can do nothing but instead I don't think that is true. If you play with mentality, in football you can beat every team."