If success is judged purely in terms of trophies won, then no-one in English football management history can match Alex Ferguson.
The 64-year-old Scot has guided Manchester United to 17 major trophies since his appointment on November 6, 1986.
Including his success in Scotland with Aberdeen in the early 1980s, his overall trophy haul stands at an unprecedented British record of 27.
His 20 years at Old Trafford make him United's second-longest serving manager behind Matt Busby, another Scot who, like Ferguson, was knighted for his services to football and most significantly for leading United to victory in the European Cup.
Ferguson has been in charge of United for more than 1,100 games, the majority of them victories, but in his autobiography Managing My Life he said he had endured periods of doubt at the club.
In mid-1995, when he set about forging the team that would go on to win a European and domestic treble four years later, Ferguson felt his position might be being undermined in the boardroom.
But for most of his reign Ferguson has led United forward with a single-minded and steely approach which many feel is the greatest secret of his success.
"He is a man with a mission," wrote former United midfielder David Beckham in his book My Side.
"It's why so many people admire him so much. It's also why he winds so many other people up.
"Whatever the gaffer says or does it's never: 'I want this for Alex Ferguson'. It's always: 'I want this for the club'.
"He is Manchester United through and through. I'd say his drive was more important to our success than anything else."
OLD TRAFFORD
Ferguson's belief in his ability and his vision for long-term success certainly paid off at Old Trafford, where the league title had not been won for 26 years before the club's 1993 success.
Gary Pallister was part of the team that ended that drought and also shared in three more championship triumphs.
"Everybody realised he had been trying to alter everything there, especially the scouting system and the youth policy," said Pallister.
"He wanted to bring a lot of young kids through and I think everybody at the club, and certainly the chairman and the directors, even in the dark days, could see that he was working towards an end."
A key part of Ferguson's successes with young players like Beckham, Ryan Giggs, Paul Scholes, Nicky Butt and Gary and Phil Neville followed the work done by youth team manager Eric Harrison, who guided them to victory in the 1992 Youth Cup final.
"People did not realise how much he (Ferguson) used to watch the youth team," Harrison told Reuters.
"When the first team were playing at home he would come to The Cliff (training ground) and watch about an hour of the youth team game before shooting over to Old Trafford.
"You didn't have to keep telling him that such and such was playing well. He knew every player.
"What was very helpful to me and the club was that if ever we were chasing a young player he would go anywhere to see his parents," added Harrison.
MASSIVE MOTIVATION
"If anybody came to the club he would make sure they were given a good apprenticeship and if they were good enough he would give them a chance in the first team.
"I have never known him to let anyone down and that was a massive motivation for me and the parents."
When Ferguson controversially allowed Mark Hughes, Paul Ince and Andrei Kanchelskis to leave Old Trafford in 1995 he did so knowing he had a conveyor belt of homegrown talent to take their places.
Harrison also watched Ferguson work at first team level, often sharing a dressing-room and dugout with the senior coaching staff.
"He has an awful lot of qualities but his biggest is his ability to inspire players," said Harrison.
"It could be the biggest game ever but he could calm players down if they needed it just by saying 'look around the dressing-room and see who you are playing with'.
"He didn't actually say it but it was as if to say 'with the quality and characters here you can't get beat'."
Harrison believes Ferguson's 20-year reign at Old Trafford has made him the finest manager of his generation.
"There was no doubt about that," he said. "Nobody at Old Trafford thought you could emulate Sir Matt Busby or beat his record. But he did and that tells the tale.
"Sir Matt was one of the greatest ever but even he has been outdone."