Mancini's Blues lie five points behind United but can cut the gap to two with victory at Norwich in today's lunchtime kickoff.
However, Mancini has stressed that this is too big a gap to overcome with a team of United's experience leading the pack.
"They can't have pressure, United. It is impossible. I think they will just win the title, they don't have pressure. For [their experience], and because they have five points, it is correct that they think this championship is finished.
"Five points are too much with five games to go."
If City triumph at Carrow Road, United can re-extend the lead to five points by defeating Aston Villa at Old Trafford on Sunday.