United have won their opening three group games and another victory over Braga in Portugal on Wednesday night would book a spot in the last 16 of the competition.
With Nemanja Vidic, Phil Jones and Chris Smalling all currently injured, Ferguson has been left with just the veteran Ferdinand and Jonny Evans as his fit senior centre-halves.
Though Ferdinand has only made one appearance in the Champions League so far this season, the United boss does not want to put too many demands on the 33-year-old's fitness.
"The game in Braga will give me a chance to utilise my squad," said Ferguson. "I'll be making some changes.
"If we can get the win it's better, but we want to make sure we qualify first. If we do, it gives me options to utilise Smalling and Jones.
"Then we can make sure that Ferdinand is fresh for all these games. I won't have to worry about playing him Saturday, Wednesday, Saturday, Wednesday.
"That's an important issue. I don't expect Vidic to be back until Christmas so it adds back-up in that respect."