Manchester United's pain at losing at home last night in the Champions League was compounded by the news that midfielder Tom Cleverley is a major doubt for the Manchester derby at the weekend.
Cleverley had to limp off during the defeat by the Romanian side Cluj, after picking up a calf strain.
"Tom felt his calf a little bit," said Ferguson.
"We will assess it in the morning but it is not good news."
The better news for manager Sir Alex Ferguson is that he believes Wayne Rooney will be firing on all cylinders against City.
Rooney was the only player to retain his place against Cluj from last weekend's narrow win at Reading.
Ferguson felt the run-out was an essential step towards Rooney regaining full fitness following his recent absence with tonsillitis.
"Wayne has another 90 minutes under his belt and hopefully by Sunday he is in real top form," said Ferguson.
"He is approaching that now but Sunday will be a different kettle of fish altogether."