Manchester United legend Peter Schmeichel has said he is "shocked and sad" after it was confirmed that Sir Alex Ferguson is retiring after more than 26 years at the Old Trafford helm.
• Brewin: Sudden end to legacy
• Potential successors
Schmeichel conceded he was "so disappointed" by the news that the manager who helped to make him one of the world's greatest goalkeepers in the 1990s was stepping down.
The Dane, who was part of Ferguson's famous Treble-winning team of 1999, was struggling to believe the legendary United boss had called it a day as he insisted there must be reasons why he had picked this moment to step aside.
"I am shocked, I can't make any sense of the timing and this has come as an absolute bombshell," Schmeichel told Sky Sports. "I really honestly don't know what to make of it. I'm sad and disappointed. I was so happy what we have done this season, taking the Premier League title home and now I'm very, very sad.
"He always said he would retire the day when something in his life wasn't right. Maybe it is something we don't know about. Maybe it's his hip operation - I can't see him retiring over that, but until he sits in front of the media and tells us why, we can only guess and guess.
"I'm sure there must be something there we don't know about. He isn't going to retire for the sake of retiring and it is really difficult to make sense of this. I see him regularly, I speak to his regularly. He is not a regular 71-year-old man. There must be something we don't know."
Schmeichel went on to endorse Everton boss David Moyes to succeed Ferguson, as he suggested the appointment of a short-term manager could do long-term damage to the legacy left behind the club's greatest manager.
"What we are looking for is not someone who can come in for ten months, but someone who can stay in and produce the same kind of stability as Sir Alex Ferguson has done," added Schmeichel.
"When we talk about David Moyes, he has been at Everton for more than a decade on limited resources and he has done a fantastic job. He is Scottish, but is he made from the same cloth as Sir Alex? I don't know.
"What we need is stability and longevity. This guy knows how to stay in a job for more than three years and that's the most important thing.
"There are going to be major changes at the club this summer with David Gill stepping down so the more stability we have the better and David Moyes sounds like a good solution. A lot of names will be thrown around, but we have to wait and see what happens."
Former United captain Steve Bruce has joined his old team-mate in paying tribute to Ferguson, expressing his "shock and surprise" at the timing of the retirement announcement.
"Everyone is in a state of 'wow'," Hull City boss Bruce told talkSPORT. "It had to happen sometime, but I didn't see it coming. He has this incredible work ethic about him and he likes to get up and work and that is the one thing you learn from him. No one works harder than he was, whatever he achieves. I hope he enjoys retirement.
"Make no mistake, he has built the club to a degree that it will be strange for him not to be there. He will be a huge miss around the place. He just has this amazing presence. It will never be repeated what he has achieved. He is undoubtedly the greatest there has ever been."
Ex-Ireland defender Paul McGrath, whose place Bruce took in Ferguson's United team, says Ferguson broke his heart when he showed him to the exit door at Old Trafford in 1989, but concedes he has grown to grudgingly admire his success inspired by the club's greatest manager.
• Have your say: Can United win without Ferguson?
McGrath says his frustration at the treatment he experienced from Ferguson left him scarred for many a year, but the has praised his former nemesis after he confirmed he will retire later this month.
"I found it very difficult to toast Alex Ferguson's early successes at Manchester United, but it has become impossible not to have huge respect for this remarkable manager as he continues to notch up trophies with relentless hunger," said McGrath.
"There was plenty of resentment bubbling inside me when Ferguson showed me to the exit door at Old Trafford and at the time, I remember thinking he would not be too far behind me in getting the boot from United.
"If I'm being honest, that is what I was hoping would happen and I didn't say a word to the man for the first five years after he threw me out of United, as I had a lot of animosity towards him for ending my career at the club.
"The likes of Jaap Stam, Ruud van Niselrooy and Roy Keane were all dealt with in the same way when the boss decided their time was up at Old Trafford and you leave with plenty of regrets because that is such a fantastic football club to play for.
"However, 24 years since my United career came to an abrupt halt, Ferguson is still at the top of his trade and after winning a 13th Premier League trophy. You can only admire the man and the success he has had has been remarkable."
McGrath believes Ferguson's successor will have 'huge boots to fill' as he admitted the next Manchester United manager faces a thankless task.
"It will be impossible to emulate or better what Sir Alex Ferguson has done," he added. "It just wouldn't happen in the modern era."