Giggs was not involved in United's 4-0 win over Norwich City at the weekend, but will take part at Old Trafford tomorrow.
"He played against Queens Park Rangers, we always like to keep him fresh. Tomorrow he will be involved at some point whether he starts or is on the bench. His experience will be vital to us," Ferguson told reporters at a press conference.
Meanwhile, Ferguson also admitted that he will "pay respect" to Madrid. He added: "If you're preparing for a game of football at our level you have to pay respect to the strengths of the other team which we do for every team - the shape, tactics, who the best players are, etc.
"You're doing your job and that applies tomorrow, but we know about the strengths of our team anyway. We know our strengths, our pattern and how to go about these games and hopefully that will help us tomorrow."