Alex Ferguson admits his hard-line approach to disciplining his Manchester United stars could have cost the club Premier League titles.
Ferguson was renowned for his no-nonsense stance on players when they stepped out of line, and notoriously fell out with several big-name players.
Ruud van Nistelrooy, Roy Keane, Japp Stam and David Beckham all left United after rows with Ferguson, while Patrice Evra recently revealed he threatened to sack any player who he deemed not hungry enough to defend the club's Champions League title in 2008.
He was also reported to have fined every player who attended the club's infamous Christmas party in 2007, which provoked a slew of sordid headlines and allegations that a girl had been raped at a hotel.
In an extract from his forthcoming book 'Leading', posted on Manchester United's Facebook page, Ferguson freely admits he placed discipline at the top of his priorities as a manager, but says his approach had an impact on his side's record.
He writes: “People will give a manager plenty of opportunities to crack the whip so it’s best to pick and choose your moments. You don’t have to dish out a punishment very often before everyone gets the message.
"I place discipline above all else and it might have cost us several titles. But if I had to repeat things I’d do it precisely the same because discipline has to come before anything else.
"Discipline was drummed into me from an early age. On school days my dad would always shake my leg promptly at 6am. Maybe that's why, a couple of decades later as manager, I got into the habit of appearing for work before the milkman arrived."