Just a week after the derby defeat that left them six points adrift of their Barclays Premier League title rivals, City produced their best performance of the season at St James' Park.
And, ahead of United's trip to Swansea on Sunday, Ferguson believes his players should take note.
"It was a wake-up call for us," said the Red Devils chief.
"City and ourselves will be battling it out and they played really well for the first 20 minutes.
"But we expect a challenge. It is what we are good at."
It is why Ferguson is approaching the festive programme with such a clear focus, believing if his side have retained their present league leaders status after they have been to Wigan on New Year's Day, they will take some stopping.
"I look at December as an opportunity to gather points," said Ferguson.
"If we are top of the league on New Year's Day we know fine well, and so does everyone else, that we are going to be in the ball park at the end of the season."
Five fixtures in 22 days is a test of every side's stamina, so, after a glut of injuries, Ferguson is delighted to have only Rafael, Nani and Shinji Kagawa on the sidelines.
And he is particularly pleased that skipper Nemanja Vidic is back in the fold after virtually a year on the sidelines.
"Nemanja is one of the best, a penalty box defender, there is no doubt about that," said Ferguson.
"People have spoken about us losing goals. I would hope that stops, or reduces it a good bit anyway."
United did the double over Swansea last term but Ferguson acknowledges the south Wales outfit may be a tougher proposition this time around as Michael Laudrup seems to have brought even more improvement from one of the most watchable teams in the top flight.
"Swansea have made a lot of progress over the last few years," he said.
"They have the courage to play their football, which is good.
"At this time of year all these games are challenges because they come thick and fast and utilising the squad will be important.
"Hopefully we can get through it and be in the same position as we are now."