N'Zogbia is to see a specialist in his native France to try and assess the extent of the setback suffered in a training ground collision with midfielder Gary Gardner last week. It adds to an already lengthy injury list with full-back Alan Hutton now on the sidelines with a calf injury.
McLeish said: "Charles is going to get specialist attention in Paris. We've just got to see if his knee ligament is going to take much longer (to heal). But we think it's a medial knee ligament problem, maybe three or four weeks out.
"It happened in a training ground collision with Gary Gardner. They banged knees together and Charles kind of opened his knee up a little bit."
Hutton is facing at least two weeks out and will miss the next two games with Chelsea and Liverpool with the setback sustained in the 3-0 defeat at Arsenal on Saturday.
McLeish said: "Alan Hutton came off with a calf injury against Arsenal and he could be out for two or three weeks. He'll need a scan."
Villa are already without long term injury victims Darren Bent, Richard Dunne and Ciaran Clark.