For both managers, it seems to be a premeditated decision to either hype or undermine the game knowing City faltered in March and the beginning of April when the pressure for them to be champions was at its most intense.
"The derby is always the game of the year," he said. "For the supporters, a derby is always a different game to the others. It is important for the city...But for us it will just be one more game, not because we fight for this or for that, and after it there are another two games, very tough games."
Though the prize is obvious - victory would put the Blues top on goal difference with two games of the season remaining and in pole position to claim their first championship since 1968 - Mancini is adamant the game is no more significant than any other.
It will maintain a quite remarkable sequence of fixtures involving the two clubs over the past three seasons.
When Michael Owen slotted home the injury-time winner for United in 2009, it was billed as the sign-off to the best derby ever. Then there was a Carling Cup semi-final which United won thanks to a Wayne Rooney goal in stoppage time.
Last season saw Rooney convert that jaw-dropping overhead kick at Old Trafford before City gained revenge by emerging triumphant in a pulsating FA Cup semi-final.
Three meetings this term have been equally memorable in their own way as United came from two goals down to clinch the Community Shield in August, and established a three-goal lead in the FA Cup before ending up holding on at the Etihad Stadium against a team that had already been reduced to 10 men.
And in between, there was that awesome 6-1 win for City at Old Trafford, something Mancini does not expect to be repeated in his lifetime.
"The one at Old Trafford was a fantastic derby," said Mancini. "But it was a game that can happen only once every hundred years."