Giggs has taken the post on an interim basis after David Moyes' sacking.
Harrison told talkSPORT: "I spoke to Ryan this morning and he is absolutely buzzing. He is going to take Paul Scholes and Nicky Butt with him - the three musketeers.
"It will certainly be a different atmosphere in training and at Old Trafford and the fans will buy into it. As soon as Ryan walks out the tunnel, the place will erupt."
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