The Lokomotiv Moscow is being lined for the caretaker manager's job at Old Trafford.
Fuchs played for Rangnick at Schalke and told BBC Sport: "He has a very clear philosophy of how he wants to play, the idea of coaching and pressing - and that will never change.
"He is looking to have a personal interaction with you. I was in Vienna with the Austria national team, we had a couple of beers and were talking for a long time about the philosophy of Hoffenheim.
"But then he said 'at the moment, you're not the player for me'.
"He was very up front, very straightforward and that's what I appreciated. Two years later he said 'I want to sign you now'.
"He thought I was not ready, but that's all credit to him for being very straightforward and very realistic. He said 'keep playing, keep learning' and two years later he said 'now, you are ready'.
"It is the little things - the positioning, when to push forward and all of those things that can impact your game massively. Under him I came to Schalke, a big club and expectations were high right away, but he made me feel comfortable and appreciated. This kind of man-management is very important in the game.
"He knows what he wants and he will demand from these players to stick together and work hard together."
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