There are three types of great managerial achievers - those who have worked under high pressure at big clubs, with big players, but still consistently deliver trophy after trophy.
Then there are those who have achieved their success against the odds, in unfavourable conditions or at unfashionable clubs.
And last, but by no means least of all, there are managers who have distinguished themselves by implementing a certain style of play for their teams that has altered the way the rest of the world thinks about the game of football - a la Pep Guardiola at Barcelona.
In Sir Alex Ferguson, there is a man that has successfully ticked all three boxes at different stages of his 37-year managerial career, and rightly deserves his place alongside the Bill Shankly's, Brian Clough's, Bob Paisley's, Sir Matt Busby's and Sir Alf Ramsey's of this world, to name but a few from the pantheon of great British managers.
At Manchester United, the 70-year-old Scot, who celebrated 25 years in charge at Old Trafford back in November, has built a dynasty whilst rewriting the history books in Lancashire on his own. A lasting legacy that will forever be remembered, not only by Red Devils fans, but football supporters the world over.
Ferguson has proved he can thrive in any environment. His man-management skills tested to the limit, whether that was dealing with your multi-millionaire footballers at United, or rather more shy and retiring players from his early days north of the border.
To consistently break the Old Firm dominance of Celtic and Rangers was one thing, but guiding Aberdeen to victory in a major European final against Real Madrid represented an individual achievement that is comparable to Clough's two European Cups at Nottingham Forest. And that is arguably not even Ferguson's greatest accomplishment to date.
The 1999 treble was perhaps the first defining moment of just how successful the United boss was setting out to be, though the 90s provided numerous indications that Ferguson was ready to wake a sleeping giant.
His first league title coincided with the formation of the Premier League in 1992-93; a year after the club secured a League Cup and Super Cup double. The following season United led the table virtually from start to finish, and made it a league and FA Cup double following a 4-0 thrashing of Chelsea at Wembley in May 1994.
The next two seasons saw the breakthrough of 'Fergie's fledglings' - the likes of Gary Neville, Phil Neville, David Beckham, Paul Scholes and Nicky Butt - players that all went on to become important members of the Manchester United team over the coming years.
1996–97 saw Ferguson guide the club to their fourth Premier League title in five seasons, and after successfully navigating the Red Devils to the Champions League semi-finals, where they lost to Borussia Dortmund, the team was ready to make its mark in Europe.
However, a trophy-less season followed as Arsene Wenger's Arsenal side pipped them to the title, and shock exits from the Champions League and FA Cup left United and Ferguson licking their wounds. But my how they bounced back.
1998–99 saw the club winning an unprecedented treble of the Premier League title, FA Cup and Champions League, with the manor of the European victory epitomising the brand of exciting football that had become synonymous with Manchester United.
Later that summer, Ferguson received a knighthood in recognition of his services to the game.
The turn of the century presented new challenges for Ferguson and Manchester United - a test of the club's credentials for longevity as one of the leading forces in the country being the most important.
Ferguson's ability to constantly evolve and reinvent teams with tactical changes has resulted in a particularly fluid and adaptable approach to modern-day football.
His most recent teams, which have won four Premier League titles and reached three Champions League finals in the past five years, have developed a devastating counter-attacking style that has influenced other teams across the world.
The only question that remains, is how will it all end? The domestic challenge of the rising force of Manchester City, and the European dominance of Barcelona look like two of the toughest tests Ferguson has ever faced.
But those who may doubt his ability in the face of adversity would do well to remember past history. Few expected him to win nine major trophies with Aberdeen, even less to end Liverpool's English dominance.
Regardless of the outcome, Ferguson's legacy as one of the greatest-ever football managers is already secure.
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