Manchester United's underperforming players are in for a "culture shock" following confirmation that Louis van Gaal is to take over at Old Trafford after the World Cup.
Van Gaal's fearsome reputation precedes him into the post and he will make it plain that he will accept no repeat of the dismal recent campaign.
Former United and Liverpool striker Michael Owen sent the warning to his old team-mates while also praising the appointment of Ryan Giggs as Van Gaal's number two.
Owen tweeted: "If reports are true, Van Gaal's appointment will be a culture shock to the current squad. Good to see Giggs kept on. Board directive?"
Veteran United defender Rio Ferdinand, who recently confirmed he will be ending his 12-year association with the club, tweeted: "Good luck to Louis van Gaal as the new manager of @ManUtd also to Giggsy as no.2. Hope they get #mufc back to the top where we belong."
Former United midfielder Ray Wilkins said he had no doubt Van Gaal would be up to the task of managing United.
Wilkins said: "He's obviously a man of great experience and has managed some great clubs, so he comes with a great pedigree.
"I have no qualms whatsoever that he will do a good job at Old Trafford.
"The big problem they have is that the recruitment of big players should have started already.
"Van Gaal has a massive task on his hands in taking Holland to the World Cup and it's going to be difficult for him to hold the two things down for now.
"They need five or six players and we have already heard there will be numerous players leaving Old Trafford.
"It is very important those players are brought into the club because at the moment they won't be able to cope in the Premier League with the players they have. They need new blood."
Former United keeper and fellow Dutchman Raimond van der Gouw believes his national team coach is the correct appointment, as he said: "Yes, I think he's absolutely the right man.
"If you look at Louis van Gaal, he has a lot of experience. He has done a very good job in Europe – first of all at Ajax in Amsterdam, after that at Barcelona, and also Bayern Munich.
"He's a very good and experienced manager for Manchester United.
"David Moyes doesn't have the same experience. He was not very lucky this season."