Sir Alex Ferguson has claimed Manchester City "might have fallen apart" this season had it not been for the fact they had the Barclays Premier League title in sight.
Both Manchester clubs head into the final game knowing they could end up as champions.
However, City have the clear edge thanks to their goal difference advantage, which means if they beat QPR at the Etihad Stadium it would secure them their first title since 1968.
It represents a major achievement for manager Roberto Mancini, who has had to deal with numerous issues, including Carlos Tevez's lengthy absence from the club and Mario Balotelli's erratic behaviour.
"It is obvious all the things he has had to deal with," said Ferguson. "If he didn't have the closeness to win the league, it might have fallen apart."
Instead, City look set to be crowned champions, setting United a challenge Ferguson likens to the one Jose Mourinho laid down following his arrival at Chelsea in 2004.
"We had to contend with Jose's management style, which was very effective," said Ferguson.
"He did a fantastic job there. You knew you were competing against a very clever manager. You weren't just facing the money, you were facing a very united squad.
"They were hard to beat. City - quality-wise - are very similar to Chelsea at that time. Some of their 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."
Ferguson has admitted it will be agony on Sunday waiting to hear whether Manchester Sir Alex Ferguson has admitted it will be agony on Sunday waiting to hear whether Manchester United can profit from "something stupid" happening to Manchester City.
United head to Wearside for their final-day encounter with Sunderland knowing if City win, there is nothing they can do to prevent the league championship heading across town for the first time since 1968.
Ferguson expects City to come out on top against relegation-threatened QPR. However, while there is still a chance, the United boss will not abandon the fight.
"It is a last game of the season thriller," he said. "It is fantastic for the neutral and agony for both clubs.
"I expect Manchester City to win. But as long as human beings are what they are, you never know.
"You just hope something stupid happens."
Ferguson admits it will be agony on Sunday waiting to hear if United can profit from "something stupid" happening to City.
United head to Wearside for their final-day encounter with Sunderland knowing if City win, there is nothing they can do to prevent the league championship heading across town for the first time since 1968.
Ferguson expects City to come out on top against QPR. However, while there is still a chance, the United boss will not abandon the fight.
"It is a last-game-of-the-season thriller," he said. "It is fantastic for the neutral and agony for both clubs.
"I expect Manchester City to win. But as long as human beings are what they are, you never know. You just hope something stupid happens."
The straw Ferguson is clutching at stems from the knowledge a QPR side managed by United old-boy and former City boss Mark Hughes will start at the Etihad Stadium needing a point to secure their own Premier League survival.
Ferguson said last week he wished Hughes was playing.
But he is confident the toughness that characterised Hughes throughout his playing career will transmit itself to his players, many of whom could be facing uncertain futures by 5pm on Sunday evening.
"Probably most of the players will be put on the transfer list," said Ferguson.
"A lot of their salaries will be halved from what I can gather. It is a dramatic thing for QPR. They have invested a bit of money and it could a big effect on the players and club."
Given the way he was treated by City, who leaked confirmation that Hughes was leaving on the morning of a game he was in charge for, the QPR boss has plenty of personal incentive to deny the Blues.
Not that Ferguson believes revenge will be a motive.
"Revenge is never a word I use," he said. "I don't think it is productive.
"But it would be ironic if that were to happen. The way he was sacked was terrible. His wife knew before him.
"It was a shock at the time but I don't think that will matter to Mark that much.
"He was a warrior as a player and all his teams seem to mirror him."
QPR, who conceded six at Chelsea a fortnight ago and have collected just two points from their last 12 Premier League away games, have little chance of becoming only the second team to deny City a home win this season.
Yet Ferguson feels parallels can be drawn between their task, and the one his own Aberdeen side faced exactly 29 years ago, when they took on Real Madrid in the European Cup Winners' Cup final.
"I had 11 home-bred players and the oldest was 27," he said.
"That is QPR's challenge - to do an Aberdeen. Of course, the odds are stacked against them. City are in good form and they are at home.
"But it will not be easy for City. The pressure on them will be enormous. The disappointment of losing the game would be unbelievable."
Even if City do not make the "stupid" mistake Ferguson says it requires for his team to land a 20th crown, he will not back down from the challenge.
"We have to do something about it," he said. "That is the only thing we can do.
"We have to meet challenges and the good thing is that we tend to get there in the end.
"In the situation we are in at the moment, it looks as though we are going to lose out this season.
"But there are a lot of young players in the squad. We don't look, in any way, as though it is the end of a period for us.
"In many ways it is the start for a lot of young players here. The challenge is very obvious to them now if we lose the league.
"As we did when Chelsea won the league two years in a row, we have to do something about it. We managed to do that. Hopefully we can do it again."
