Ferguson recently passed the legendary Sir Matt Busby as the Red Devils' longest-serving manager, having been at the helm 24 years, and is after a 19th league title for the club — who currently top the Premier League table.
If he succeeds it will see United overtake Liverpool as the most successful side in England. But despite his achievements, Ferguson has revealed that there are times when he questions his own judgement.
"Of course you have doubts," Ferguson told Sky Sports News.
"Even now when you lose games you still have that feeling of 'How are we going to recover from this one?' and you do the same things all the time.
"Management is about making decisions.
"Sometimes they're positive and good, and sometimes you maybe make the wrong decision and feel you maybe should have attacked it in a different way or maybe done something different.
"You have it with picking teams.
"We made a decision the other night, against Arsenal, to leave Dimitar Berbatov out of the team.
"It wasn't an easy one. It was very difficult to explain to Dimitar. The only way I could explain the decision was that I felt it was going to win us the match.
"And although I was proved right and we won the game, you're never sure. So doubting does come into it."
Despite such concerns, centre-back Rio Ferdinand has backed the Scot to lead the team to the landmark title.
"The manager's desire is there for all to see," the defender noted.
"It's not diminished over the years. The experience the manager passes on, just little bits and pieces, is huge.
"He'll chuck something new and different out in a team talk that will make you sit up and think 'Yeah he's right there'.
"If the manager's still got the hunger and desire, how can we not have the same desire? That's the example he sets.
"You see, most of the time, that the most successful teams are the ones who have got the same manager for a long period of time.
"Luckily, the manager has been there all these years. People say what a big club this is and it is, probably the biggest in the world.
"But if you look behind the scenes, there are people who have been here for 20, 30 or 40 years.
"That speaks volumes about what this club's about - continuity."