The final scenes in what is widely regarded as the best season since the Premier League replaced the first division 20 years ago will be played out at the Etihad Stadium where City take on Queens Park Rangers and at the Stadium of Light where Sunderland host United.
The mathematics are simple enough. Both have 86 points but City's goal difference is eight better than United's.
If City win they will be champions for the first time since 1968. All that could stop them is if United win by nine goals.
If City lose or draw and United win, then United will retain the title they won last year and be crowned champions for the 20th time.
With the time for the final action almost upon them, Ferguson and Mancini faced the press for their last pre-match conferences of the season on Friday.
Ferguson indulged in his usual psychological mind games by saying City could suffer "untold damage" in the unlikely event that they miss out on winning the title.
"I think the disappointment of City losing out would be unbelievable and it's untold at this moment in time what effect it could have on them," said Ferguson.
"On the face of it you expect City to win and so do I. But as long as human beings are human beings you never know. You hope something stupid happens.
"We have to win and that's what we have got to focus on. It's the last game of the season, it's fantastic for the fans, for the neutral, fantastic for the media but agony for both clubs - although it will be more so for City if they lose it."
"Some of their (City's) players have had outstanding seasons. When you win the league you need five or six players who are consistently good all the time.
"City have had that this year and the manager, for most of the part, has done well.
"City are not going to go away, with the money they have got," added Ferguson. "They will buy more players for sure this year. But they can only buy so many and keep the balance for so long before they disrupt things.
"We've got our own ideas about where we're going in the summer. I think we'll be ready for the challenge. No matter whether it's as champions or runners-up, we'll be ready for it."
Mancini has had to deal with numerous difficulties this season including Carlos Tevez's lengthy absence from the club and Mario Balotelli's erratic behaviour.
Mancini said Sunday's game was not a personal battle between him and his opposite number Mark Hughes, once a United player and the man sacked as City manager to make way for Mancini in December 2009.
QPR need a point to avoid relegation, a point that could also deny City the title and give Hughes some revenge for his sacking.
"For me, they (QPR) are a good team, they don't deserve to stay at the bottom," said Mancini.
"They want to do everything to stay in the Premier League and for this reason I think it will be a tough game.
"I don't know him very well but it is not Mancini against Hughes or Hughes against Mancini. It is City against QPR.
"One team plays for the title, the other plays against relegation."