In a gilded career stretching way beyond the normal confines of football management, Alex Ferguson has not made many mistakes.
But he is happy to admit that, back at the turn of the century, he made a serious error of judgment. "An absolute disaster," is what he later called his announcement that he was going to step down at the end of the 2001-02 season.
The idea was he would go out in a blaze of glory, leading Manchester United to triumph in the Champions League final at Hampden Park.
Instead he presided over an odd deflationary process at the club, a weakening of resolve as eyes were taken off the ball, as players and staff jostled for position ahead of the arrival of a new leader. It was the footballing equivalent of a lame duck presidency.
After he reneged on his decision and returned to the fold – to the huge relief of every United fan who had heard Sven Goran Eriksson had been lined up as his replacement – Ferguson insisted that the next time he retired he would do so without a timetable, stealthily and suddenly. And he would have to go sometime.
Ferguson has always been a manager aware of history. Not just in the accumulation of silverware, not just in his astonishing success in wresting back the initiative in the Premier League from five managers, but his position in the gilded story of his club. Others might talk of legacy, he has always wanted to leave a real one. And in United's past there lurks the most telling example of how not to proceed.
When Matt Busby retired in 1969, the club did almost everything wrong in its succession planning, not least in the condition of the team the great man left behind, a side that needed rapid upgrade but was instead allowed to ossify.
Initially it seemed a sensible move appointing Wilf McGuinness, imbued as he was in the club, immersed in its rhythms and traditions. But he was also seen as a puppet, controlled by the former boss who had migrated upstairs to the office of club president, clearly deciding still on transfer policy.
McGuinness' management was so error-strewn, Busby was obliged to don his tracksuit to sort out the mess within a year. Sadly, when he eventually gave way to Frank O'Farrell, his shadow was still cast across the Stretford End. And O'Farrell sank under the shadow.
Ferguson's departure has to be total.
There can be no lurking in the corridors, no hostage to cliques or power bases. He has to go completely, turning up only occasionally in the directors' box, benevolently ruffling hair and signing autographs.
It is in the choice of his successor that United's hierarchy need to ensure they are at the top of their game.
Things have changed since Busby's day, the organisation operates to another level of business altogether. It simply could not countenance the kind of decline that saw United sink into the second tier after he departed the scene.
Sure, Ferguson's legacy will help any new man. But to maintain the club's two-decade long momentum, they need a strong, experienced manager, one sufficiently robust in his self-esteem not to wilt as he stands in the technical area at Old Trafford with his predecessor's name written across the top of the stand.
United have no doubt been working at it for some time, identifying potential candidates. He himself will want to be part of the process. Hints of inside thinking has been there in questions raised by senior figures about some of those reckoned in with a chance, about Jose Mourinho's fondness for politicking or David Moyes's lack of big-budget experience.
Now the talk can no longer be about those who don't fit, but the one who does. The Old Trafford boardroom has proven itself to be adept at securing commercial partnerships with Malaysian snack food producers and Bulgarian telecoms. Now it needs to make the connection that matters. On this hangs their very future. (© Daily Telegraph, London)