Manchester United had already qualified for the last 16 of the Champions League but lost to minnows CFR Cluj at Old Trafford on Wednesday ahead of Sunday's derby at neighbours Manchester City, and manager Sir Alex Ferguson has asked his senior players to buckle up.
"Now the experienced players have to get their act together - as simple as that. We qualified early in Europe. After that we experimented and gave some young players a bit of experience," the Sun quoted Ferguson, as saying.
United head to the Etihad after only a second defeat in 37 home Champions League games.
The Red Devils were already assured of topping Group H before going down to the Romanians.
Luis Alberto's 30-yard stunner won the game but United looked uncertain defensively again.
Ferguson added: "They did the job quite well. We were beaten by a wonder goal but their commitment and composure was good and they're still young. We didn't deserve that goal. We had a lot of good chances and to lose a goal like that, you can have no complaints about that."
"Unfortunately, Tom Cleverley has got a calf injury, we'll have to see what he's like.
"And the positive thing is that we were able to rest players ahead of Sunday," he added. (ANI)