When Sir Alex Ferguson retires at the end of the season Manchester United and the Premier League will never be the same again.
The 71-year-old has been like the godfather of football; he almost runs the Premier League, strikes fear into referees and people at the FA, and there will never be another one like him.
There's nothing more for him to prove now and, after winning the league title back from Manchester City, he can bow out on a winning note.
He'll certainly be a tough act to follow and, looking back on his time at Old Trafford, it's hard to pick out one of his many achievements above all others. For me, the thing that stands out was his ability to repeatedly build new, successful teams.
Time after time he would re-build his squad, bring in new young players and create sides capable of matching the achievements of their predecessors. When they won the treble in 1999 we asked 'where do they go from here?', but they just kept on winning.
There's no doubt about it, United would never have won the number of trophies they have without him. He had the ability to make average players good players and good players great players.
He also commanded an incredible level of respect from his players in an era when respect, in all walks of life, not just football, has gone out the window.
From when he first arrived at Old Trafford, when the league was mainly made up of British players, to the modern era of foreign stars and multi-millionaire footballers, he has always been able to control the dressing room in a way so many mangers struggle to do.
I didn't play for Ferguson but I knew what it was like to play against him and he was like a 12th man for United. The amount of times he'd make a substitution and win a game was incredible.
He was always ready to gamble - and I won't forget United scoring two late goals in a 1999 FA Cup fourth round match against the Liverpool side I was playing in to win 2-1.
But, that's the way he was: he instilled a belief at the football club that they'd never get beaten.
He's also a great advert for what clubs can achieve with British bosses and a commitment to consistency. There's no way an Aberdeen boss would be given such a big opportunity today, while I'm sure his lean first few years would have led to him being sacked if he was setting out in the hire 'em, fire 'em world of today.
And that's why I'm pleased David Moyes is being strongly considered as his successor.
Ferguson has left a young, vibrant side with loads of potential for the man that follows him and I believe Moyes can be the man to take the club on from here.
I'm a massive fan of the Everton boss but, although he'll need a lot of help at first and the right staff around him, talk about his lack of Champions League experience making him unsuitable is a load of rubbish.
We're so obsessed with foreign managers in this country but Moyes is a fantastic coach and if he gets the job he'll do as well as anyone.
Of course, it's going to be incredibly difficult to follow him. If his successor thinks about the ghost of Ferguson and what he's achieved he wouldn't sleep at night. All he can do is focus on how to take the team on.
For instance, the Wayne Rooney situation needs addressing, there is talk Robert Lewandowski could come in and some players need to be added.
But United, even without Ferguson at the helm, will remain one of the biggest clubs in the world and the young squad he's leaving present a huge opportunity for someone.