Ferguson accepts his side never recovered from tossing away a two-goal lead against Swiss outfit FC Basel on matchday two, a further home draw with Benfica helping to condemn them to a group stage exit from the Champions League for the first time since 2005.
United have found it no easier in the Europa League, where they almost contrived to get knocked out despite at one stage boasting a three-goal aggregate lead to Ajax and Ferguson said: "It is a game in which we need to waken up."
He added: "Some of our European form this season has been disappointing. I don't know whether we are making too many changes.
"Obviously I will be playing a strong team tomorrow and hopefully that makes a difference because it is going to be a very difficult game."
Domestically, Sunday's win at Tottenham was United's 10th on the road this term, twice the number they managed in the whole of last season, and leaves them just two points adrift of City having completed their most testing run of fixtures.
"It is going to be an exciting time for the club," said Ferguson. "We had a fantastic result on Sunday. Hopefully that gives us the impetus to have a real go at this league."
It is why Ferguson is so glad Tom Cleverley has recovered from an ankle injury that has sidelined him for a fortnight and Anderson is in line to make his first start for four months after finally shrugging off a knee injury from which it appears he tried to come back too soon.
"Anderson was a substitute on Sunday and he is back, fit and training very well," said Ferguson.
"He will be involved. It is good to get a player of that quality back for the run-in."
Source: PA
Source: PA