Sir Alex is looking to win a 20th title for Manchester United.
Manchester City may have overcome an eight-point deficit to win the title last season, but after this weekend's results, there is absolutely no doubt.
The title race is over.
Manchester United have been simply irresistible this season. Although they have been lacking at times defensively, their brilliant forward line, led by Robin van Persie, have always ensured that the points have kept on rolling in.
Whilst United have been relentless, City have stuttered. Their performance against Southampton was undoubtedly their worst of the season, but they have played poorly on a number of occasions this year, and you simply cannot afford to do that when you have a rival like United trying to regain their title.
Although football is a team game, there is one man in particular who has made the difference for Manchester United, and that man is Robin Van Persie.
Both Manchester clubs were vying for his signature in the summer, and Roberto Mancini will now surely be kicking himself that he couldn't persuade the outstanding Dutchman to ignore the overtures of Sir Alex Ferguson and join the project at Manchester City.
It has been a disappointing season for the blue side of Manchester. After winning the title in dramatic fashion last season, they have now gone backwards.
They didn't strengthen in the summer as they should have. They would have been better off going out and buying one world-class player, like Van Persie, instead of three distinctly average ones in the form of Scott Sinclair, Jack Rodwell and Javi Garcia.
Some of Mancini's team selections also leave a lot to be desired. How Gareth Barry still commands a first-team place is baffling. He wouldn't get near the Manchester United first eleven.
Where this will leave Mancini at the end of the season is uncertain. Ferguson, though, is looking more powerful than ever. He is clearly in the middle of building yet another great team and putting Manchester City back in their place.