Mehmet Scholl has warned that the Old Trafford outfit will have a disciplinarian in the form of their potential new boss.
However, a former Bayern Munich player and the reserve coach under Van Gaal has warned the United players of what they are getting into.
Mehmet Scholl has stated that the experienced coach is a disciplinarian but also a top-drawer manager.
"He's very strict and severe,” the retired midfielder told The Guardian.
“So the players just have the chance to follow him or they are out and he takes the next players. He's very good with young players. I think everywhere he was he had some problems with big players and the staff.
"There are 26, 27 players and he is looking for the 14 to follow him – 14, 15, 16 to follow. His thing is not the motivation [man-management]. He's good in motivation but this is not his main character thing.
"His thing is really working on the pitch – that's brilliant. And that's how the players learn. You know by yourself that if you learn from somebody you are curious, you want to learn more.
" Some of the players, I can tell you, like Rooney, I don't think he has to learn anything more. So that will be difficult for him if the coach says: 'You have to do it in a completely different way. Whatever you did until now, change it.'"
One of the reasons that United are thought to want Van Gaal is to get Robin van Persie back fit and firing.
The United players struggled to take to David Moyes’ training methods and as such it will be interesting to see how they would respond to the Dutchman.