The 23-year-old impressed while on loan with the Scottish side four years go and his former manager believes he has what it takes to make the next step-up to United.
“I always thought James was the best technician of a ball I've seen," McInnes told The Press and Journal.
“I haven't seen someone who manipulates the ball in the way he can and that potential is really being realised now.
“James has said that coming to Aberdeen has helped be the making of him because he had to grow up a bit, he had to tough things out and he had to learn how to deal with the demands of playing here.
“He was developing then and the games up here were tough for him.
“You can't say that you watched him and thought he would go from playing with us, back to Norwich, on to Leicester and then potentially to a club like Manchester United so quickly.
“But you see him now, he has developed so much that I think he could play for any of the big clubs in England. That's how good he is.
“The improvement in him over the last two seasons especially has been massive and it shows what can be done."
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