Sir Alex Ferguson says he struggled to accept new managers changing his legendary Manchester United team after he retired

• EXCLUSIVE: Sir Alex Ferguson says he found it "hard to accept" new managers changing his team after he left Manchester United.
• A large number of the legendary manager's former players were released or sold within a year of his retirement.
• "These guys have won the league by 11 points. Give them another year," Ferguson told Insider.

Former Manchester United manager Sir Alex Ferguson has told Insider that he found it "hard to accept" new managers changing his team after he retired from the club.

Speaking in a lengthy interview ahead of the release of a new documentary about his life produced by his son, Jason, Ferguson told us of the disappointment he felt after he stepped down as United coach at the end of the 2012/13 season, bringing to an end a glistening 27-year career at Old Trafford.

In his final term, the Scot guided the club to the English Premier League title for the 13th time, before countryman David Moyes took over during the summer.

"I think the first year was pretty strange," Ferguson told Insider while reflecting on his career during a conversation with Sir Michael Moritz, a close friend and billionaire venture capitalist.

"And I'm not, I'm not being critical, but when I saw some of my players actually leaving the club, I didn't quite enjoy that, you know, as in: 'Why?'

"I mean, these guys have won the league by 11 points. Give them another year. That was hard to accept."

In the months after Ferguson stepped down as United's manager, veteran midfielder Paul Scholes retired aged 38.

Then, after a torrid season in which United finished seventh - its worst league finish since 1981 - Moyes was sacked and replaced by Louis Van Gaal.

Van Gaal got rid of many of Ferguson's players, selling defenders Nemanja Vidic and Patrice Evra to Inter Milan and Juventus respectively, and releasing 12-year veteran Rio Ferdinand. Ryan Giggs, who spent his entire career in Manchester also retired.

All four players had been instrumental for United during Ferguson's time as manager, making over 2000 appearances between them.

Giggs, United's record appearance maker, was a member of all of Ferguson's 13 title winning teams. Ferdinand won six titles under the Scot, while Vidic and Evra won five apiece.

"In football, every manager his own way, his own staff, his own beliefs, and that's absolutely correct to have that independence and your own beliefs," Ferguson continued, adding that he was soon able to relax and enjoy watching United as a spectator.

"That passed quickly [Ferguson's unhappiness at the removal of the players]. When the team shaped itself in a different way, I enjoyed going to the games, that was behind me.

"There was no need for me to think about what I could have done, because it was over for me. I was happy to go to the games, have my lunch before the game, have a glass of wine, and enjoy myself."

Sir Alex Ferguson spoke to Insider ahead of the release of his new movie, "Sir Alex Ferguson: Never Give In." The film is out in cinemas in the United Kingdom on May 27.