The 4-1 win was Liverpool's best result at Old Trafford since the 1930s and Ferguson said it was a reminder for the league leaders not to get carried away.
Ferguson, whose side travel to Fulham on Saturday looking to re-establish their credentials as firm title favourites, said: "For weeks we have had to listen to eulogies and compliments about how great this side is, and I have kept deflecting that and saying how tough this league is."
He added: "Everyone likes to read good things about themselves, particularly young players like to think they are the bees' knees all the time, but football's a game that comes back and bites you quite severely as we found out last week.
"That defeat was a reminder about how difficult this league is and in a way that will help us.
"We all now realise that there is a lot of work to be done. It's put us in a position to say let's get the show on the road again."
Ferguson said his players had brought the Liverpool defeat on themselves to a large extent, and that was an issue they had focused on in training since.
He added: "It's hard to defend a 4-1 defeat and we have to be absolutely clear in our mind about the reasons why it happened, and we are clear about it.
"I think it was self-inflicted and it came from mistakes we don't expect our players to make.
"You get situations like this in the run-in and the good thing is that I am used to it and quite a few of my players are used to it."
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