Robin van Persie witnessed Sir Alex Ferguson's rage at Manchester United as the Scotsman lamented two "a***hole" players back in 2013.
The Dutchman was in his first year at Old Trafford with his 30 goals integral to their title success.
But in April they lost at home to rivals Manchester City, although they still retained a double digit lead at the summit.
After the reverse two players chose to head out for a night on the town which didn't go down well with Ferguson who threatened to sell any player who followed their lead.
Van Persie told SoFoot : "During my first season with United we were 15 points clear at the top. We hosted Manchester City hoping to wrap up the title.
"We lost, but were still 12 points clear. Most managers wouldn't have made a drama out of the situation.
"But the boss got really fired up. Things got extremely heated, as two of the squad had gone out after the defeat.
"The day after the game Sir Alex had photos put up on the dressing room wall of the two players taken during their night out.
"He told the entire squad: 'Boys, if we don't win the league it's because of these two a***holes who opted to go out'.
"I know the names, but can't reveal them. The manager slaughtered them. It was amazing. He'd put up photos documenting where they were, at 2am, 3am, 4am etc, to underline just how stupid they had been.
"He didn't stop there, but warned us that if he heard of any of us going out before we'd won the league we'd be out of the team.
"He was merciless, saying: 'I don't care who you are or how many trophies you've won - if you go out before the end of the season I'll sell you'.
"After that speech I had the two hardest training sessions I've ever had in my life. We went on to win the title. A manager has to know when to be tough, and when to take the pressure off."
