Liverpool arrived in Manchester trailing the champions by seven points but stole North West bragging rights courtesy of a fine performance on their travels.
Cristiano Ronaldo's penalty put United in control before defensive mistakes from Nemanja Vidic and Patrice Evra allowed Liverpool to forge ahead by half-time courtesy of efforts from Fernando Torres and Steven Gerrard.
It go no better for a below-par United after the interval as Vidic was sent off and Fabio Aurelio and Andrea Dossena scored further goals for Rafa Benitez's rampant Reds.
Ferguson, though, believes his team's overall performance was not too bad as he backed his players to show a positive response in their next game.
Unfair reflection"It is a hard one to take because I thought, really, we were the better team and the score does not reflect that," Ferguson claimed.
"But of course when you win 4-1 at Old Trafford you deserve all the plaudits and you can't deny them that.
"If the league was starting today, you would take a four-point start.
"It was a bad day in terms of the goals we lost but I couldn't argue with the quality of play that much."
Response neededFerguson was willing to concede some of his players were not at their best but refused to point the finger at individuals.
"One or two players were a little bit short today in terms of what we expect of them but I do know the football was good, we kept driving on and they showed good energy, even though we only had two and a half days to prepare for the match, he added.
"Now the thing is to respond. It always is at this club - you lose a game and you respond. We always do."