The champions have fallen seven points behind their neighbours at the top of the Barclays Premier League but are confident of clawing back the deficit. City memorably recovered from eight points behind with just six games remaining last season and see no reason to panic with 17 left this time.
Mancini said: "Until now United played very, very well. They deserve to be on the top, maybe not seven points more than us but this is football. There are some moments during a season that even a top team like United can lose points. It is impossible to win every game like last year. We should be ready when United lose a point."
He added: "For this reason, it is important for us to go our way and to continue to win.
"We don't look at the table, in this moment the table is not important. We know we are in second position."
The gap at the top could shrink to four points or grow to 10 but even if the outcome is the worst for City, Mancini claims he would not give up hope.
Such words contrast sharply with what the Italian said after a damaging loss at the Emirates Stadium last April, when City handed United that seemingly insurmountable lead during the run-in.
Mancini said: "Everything is possible but it doesn't change the situation.
"Last year United recovered when we were five points up and after Arsenal we went eight points behind. United recovered 13 points. So we can recover 10, it is not a problem."