The reigning champions managed to produce a 2-2 draw at home against Liverpool today after trailing 2-1 with just over 10 minutes remaining but it was another slip-up following their 0-0 draw at QPR during the week.
But Sergio Aguero's 78th minute finish from an angle gave City a share of the points and a glimmer of hope to bridge the gap with United, although it now seems a very difficult task.
"Absolutely not," said Mancini when asked if City's title chances are over.
"Two years ago Chelsea were nine points behind and when they went to play at Old Trafford two games from the end (of the season) they were only two points behind.
"Two games and the championship is reopened. I don't think this is finished but probably now we have to win all the games but if not then 11 or 12 games.
"But in football this can happen sometimes.
"Last year we recovered eight points in six games so I don't know why it can't happen this year.
"We have 15 games and they (United) have to play in FA Cup and the Champions League so the season is long - three months - and we are confident.
"It is enough to recover three or four points in three games.
"For us it is important to play the derby (at Old Trafford on April 6) two or three points behind and we have time to recover these points.
"Today we didn't play like we had in the last month but we are confident."