City's 1-0 defeat by Arsenal at the Emirates Stadium last season left Mancini's men eight points behind United with six games to play, and most people were writing off their chances of winning the title.
Yet Hart and his team-mates clawed back the deficit to claim the championship with virtually the last kick of the season.
Hart remembers the events at Arsenal last season and knows how vital the game is on Sunday.
“We all recognise the importance of this game," he told The Mirror.
"We also remember how it felt when we came off the pitch at the Emirates last season, eight points behind with six games left. When you lose in that manner, it’s angry time.
"I was raging, fearing that all our hard work had gone down the drain. But when you calm down and look at it objectively, it’s not the end of the world.
"There is always a way back into the title race, and after losing at Arsenal last year, we knew we still had to play United, just as we’ve still got to play them again this season."It all worked out well in the end of Manchester City but Hart admits there was a '10-minute spell of going crazy' after defeat to the Gunners last season.
He continued: "There was that 10-minute spell of going crazy, thinking you had blown it, but then reality kicks in and it dawns on you: It’s never over until it’s over.
"You have to control your anger – you can’t be a baby when you lose. And for 10 minutes I don’t accept defeat, I won’t accept defeat, losing isn’t fair and the world is against you...
"Then the mist clears, you calm down and move on.”
City face Arsenal at the Emirates on Sunday afternoon, kick-off 4pm.