But Ferguson is confident United can bounce back and lift their title hopes by beating West Ham on Tuesday.
"We left something in Milan and there was tiredness in the team," Ferguson said after Saturday's 3-1 loss.
"But Tuesday is a massive game now. We've been responding for a long time so I don't expect a problem with that."
Rio Ferdinand will be available to face the Hammers after completing a four-game ban, while his central defensive partner Nemanja Vidic could also come into contention to start after being named on the bench against the Toffees.
But Ferguson will demand wholesale improvement after witnessing a disappointing United display, which he put down to the after-effects of their 3-2 win at the San Siro.
The equaliser changed the game a little bit. But it was the second half that let us down.
"Our second-half performance was very poor and when you are going for the championship you expect Manchester United to respond to the importance of the game."
Dimitar Berbatov gave United the lead at Goodison Park but Diniyar Bilyaletdinov equalised before Dan Gosling put the hosts ahead and Jack Rodwell sealed a fine victory.
"This is a bad result and at this time of the year we can't afford results like that," added Ferguson.
"But I don't think we will panic because it has been a funny season. Teams have been losing points that you don't expect so the very nature of the league suggests we still have a chance."
Adapted From BBC Football
hooefully,Manchester United will win the match against West Ham United on Tuesday!!
=)