The veteran midfielder missed the 1-1 draw with Real Madrid with a knee concern but had been expected to return for the FA Cup fifth-round tie against Reading.
The 38-year-old midfielder has been struggling with a knee problem that forced him to sit out the side's mid-week UEFA Champions League trip to the Bernabeu in Madrid, with the initial hope of involvement against Reading in the FA Cup fifth round on Monday.
Ferguson revealed on Friday that the veteran is sidelined for "another couple of weeks," though after having a bit of a setback.
"It is a knee injury, which has been bothering him a bit," Ferguson told reporters. "We have tried another treatment during the week. He will probably be back in another couple of weeks."
On a more positive note, Ferguson confirmed that the squad came away from Wednesday’s 1-1 draw with Real Madrid unscathed, but he will be making changes for the visit of Reading in three days’ time.
"I will make some [changes]," Ferguson said. "We want to get to the quarterfinals (of the FA Cup), and we do expect to qualify."