Mourinho will be especially frustrated by the defeat because it means he can not afford to rest players against CSKA, just days before the Manchester derby.
Mkhitaryan, 28, was left out of the squad that defeated Newcastle 4-1 at Old Trafford on Saturday and the Armenian cut a lonely figure at training this week.
Despite that Southgate decided against picking him for an ultimately weak squad for the draws against Germany and the Brazilian's, there are a only few months to impress ahead of World Cup in Russian Federation this Summer but Smalling stated that he will be looking to give Southgate "no choice" but to pick him.
They also boast the talent of young forward Dimitri Oberlin, who has already scored three goals in the group stage this season.
Romelu Lukaku endured a quiet night but he nearly risked the wrath of his manager when he lost possession and Luca Zuffi fired narrowly wide.
Fellaini saw another header go close in the 16th minute, diverting Daley Blind's free-kick delivery agonisingly wide of the left-hand post.
"It just wasn't good enough second half".
And striker Zlatan Ibrahimovic, who returned in the same match as a substitute after being out since April with a knee injury, will be on the bench again.
"Man United will be bitterly disappointed because it was an opportunity to rest players in their next game and now they've got to keep playing", Ferdinand explained.
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