Arsenal manager Arsene Wenger has paid tribute to his great rival Sir Alex Ferguson ahead of the new statue set to be unveiled in his honour on Friday.
Ferguson is to be further rewarded for his successful 26-year spell in charge at Old Trafford with the statue, which will be located outside the stand that already bears his name.
Wenger has had many heated duels with the Scot over the years but in recent times their rivalry has blossomed into that of great mutual respect between the two.
The Gunners boss still holds his old enemy in the highest regard and expects United to struggle when they eventually have to search for his successor.
"I don't remember anybody else being at the top, top level for such a long time," Wenger said. "In some ways it is scary as well because you think when this guy leaves the club, no matter of the quality of who comes in after him, it will be a huge hole.
"The club will be destabilised even if the guy who comes after him is top quality because the print of everything, the life of everything, revolves around Ferguson so much at Manchester United. He has to be immortal so the club doesn't suffer!
"His commitment is always there, you never feel that his commitment is weakened. What I admire maybe the most in him is his forward-thinking. He is always ready to move with the times and never speaks about what he has done before.
"He knows when to renew the team, when you have to make changes, and that is exceptional because you can sometimes be a little bit lazy when you have so much success. He's never been like that, he's always on his toes and he can renew what is needed, when it is needed.
"It is a job where you need to dedicate your life to football and Ferguson has done that and that deserves massive respect. He has won absolutely everything and, of course, that is something exceptional.''
Jose Mourinho, Sir Bobby Charlton and former Prime Minister Tony Blair all added their support for the Scot, who has won 12 Premier League titles, five FA Cups, four League Cups and the Champions League twice in his 26 years at United.
"He's unique, especially in the modern day," Mourinho said. "If you go back many years then you will find somebody like him, but, [it's amazing] in the modern day at the highest level, where it is really difficult to survive in our job.
"He's absolutely incredible at what he does and we can't even imagine when he'll stop, he's unbelievable."
Charlton, who is United's record goalscorer, helped appoint Ferguson in 1986 and said: "When we made the decision to go for him we didn't in our wildest dreams think that it would last as long as this.
"I won't see his like again, I'm certain of that. We're really lucky, and people are really envious of us. He was born to do this job and he's going to be with us as long as he wants. He's just a sensational manager. Others must look on in envy."
Blair was Britain's Prime Minister from 1997 to 2007 and got to know Ferguson, a supporter of the Labour Party. And the politician said: "He is one of these people that has a strength of character that immediately marks him out as a leader of people.
"He's a great competitor but he's also got huge integrity, to himself and to what he believes in. That's quite unusual in life to find people like that and when you find them they're very special.
"If you're in a tough situation and everything is coming down on top of you and you feel you're slowly getting surrounded by the people that want to put you in a deep dark pit, Alex is the type of person you'd want standing alongside you because you'd know you were [able] to give whoever came after you a good fight."
Information from the Press Association was used in this report