The Red Devils will be crowned champions for a record 19th time next Sunday, after what promises to be, for the opposition at least, a tense last-day encounter with relegation-threatened Blackpool at Old Trafford.
Yet still the doubters remain, unconvinced by the 1-1 draw at Blackburn on Saturday that ensured United would win the Premier League for the fourth time in five years.
No-one questions how good Barcelona are though, which is why Ferguson believes any criticism can be ended by beating Pep Guardiola's men in the Champions League final on May 28.
"Beating Barcelona would end all arguments about this team," said Ferguson.
"I know we are playing a terrific team but would you back against us in a big way? I don't think you would.
"We are capable of doing very well."
Ferguson knows the challenges will be coming at his team from all angles next season.
Chelsea are expected to be a far more consistent force and while such bitter disappointment this term may restrict Arsenal's ability to respond, Liverpool and, particularly, FA Cup winners Manchester City both look certain to do better than this season.
Not that Ferguson is concerned about that.
Even before United secured the championship that swept them past Liverpool, he had already pledged to remain in post for at least another season.
And there is no sense of any desire to take a back seat.
"I will not be taking it easy because we have won the title," Ferguson pledged on MUTV.
"The ambition of the club doesn't alter. It doesn't go away. That is the responsibility as manager of Manchester United.
"You always expect Liverpool to challenge us. You always expect Manchester City to challenge us.
"The great thing about us is that we accept challenges. It doesn't matter where it comes from.
"Our job is to get better and we will try to be better next year."
There are a few issues for Ferguson to resolve.
Atletico Madrid's David de Gea is thought to have been lined up as a successor to retiring goalkeeper Edwin van der Sar, while a couple of additional new faces are anticipated, including Wesley Sneijder.
But a decision about Paul Scholes' future is still awaited with chief executive David Gill not entirely convinced the veteran midfielder will extend his stay at Old Trafford.
"It wouldn't surprise us if Paul Scholes retired," said Gill on BBC Radio Five Live's Sportsweek programme.
"On the hand, we are enjoying the success we are having, so at the end of the season, he will have a conversation with Sir Alex about that.
"I am sure he will let us know his decision and we will respect it."
