The veteran German is set to take over at the Red Devils, and may even be in the dugout when they take on Arsenal on Thursday.
Hasenhuttl, who has worked under Rangnick at RB Leipzig, believes the veteran can have a big impact at the underperforming club.
Hesaid, per the Daily Echo: "I know him very well. We had two very successful years.
"He was sporting director, so I know how he is and how he works.
"He's a hard worker and he needs a good team around him. He will turn every stone around there for sure because he doesn't want any weakness in any part of his club.
"Six months is not too long to turn things around but he will have a big impact.
"I think this league is known that the best managers are working here, or it is especially the big teams, they should always look for the best possible options, in a moment he was one of these and I'm sure that he will have his impact in this league."
Asked if the two had spoken, he added: "Only a message to congratulate him on his big dream of coming to the Premier League.
"Now it has become real and it is fantastic for him, he's been waiting for this moment."
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