City head to Newcastle on Sunday for their penultimate game, leading Manchester United on goal difference.
Yet they could hardly be facing a trickier task, coming up against the league's in-form team and their brilliant 13-goal striker Papiss Cisse.
It would be enough to make anyone sweat and the Blues have only just recovered from that nightmare run when they dropped points against Swansea, Stoke, Sunderland and Arsenal within the space of a month.
Mancini cannot say whether they will succeed or fail.
However, the Italian is certain. If City's first championship since 1968 is not secured, it will not be because they choked.
"That won't happen," he said.
"It happened six weeks ago. I don't know why. Probably because we had some important players injured. But it won't happen now.
"We can lose because in football you can lose every game. But I am sure we will play a good game."
City are presently the Premier League's top scorers. They also have the meanest defence and have done the double over United for only the second time in 42 years.
By any rational assessment, they have been the best team this season.
So far though, it means nothing.
And, just as he would doubtless shake his head at those City fans who claim they would be happy to win nothing else as long as this season's title was secure, Mancini is deriving little pleasure from what his players have done thus far.
"We are the best team in Manchester. To be the best in the country we need to win the next two games," he said with a smile.
"It is not important to beat United twice or beat Chelsea. The only important thing is to win the championship at the end."
Nevertheless, Mancini believes City's changed mentality comes from a previous meeting with United.
Not that six-goal drubbing in October, but the FA Cup defeat in January, when it appeared United would exact maximum revenge but ended up clinging on for a 3-2 win.
"For playing against United the FA Cup game in January when we lost 3-2 was really important," he said.
"It wasn't the 6-1. That game was easy.
"But in the FA Cup, we had to play with 10 men for 80 minutes and we were also 3-0 down.
"We recovered that game, and although we lost, they didn't have a shot in the second-half, even though they had 11 players and we had a chance to score the third goal.
"It changed our mentality against them."