Sir Alex Ferguson had wanted to reveal his retirement plans on the Old Trafford pitch after his final home game as Manchester United manager.
The 71-year-old went public on his imminent departure on Wednesday morning after British newspapers reported he was set to end his 26-year reign.
But sources told ESPN that Ferguson, who traditionally addresses the Old Trafford crowd after the last home match of the season, had originally intended to wait until after the final whistle of Sunday's game against Swansea and then surprise United fans by saying he was making way.
Instead, he thanked the supporters for their backing and urged them to get behind his successor, David Moyes, when he took the microphone in the centre circle.
Because the club and the supporters knew the 2-1 win over Swansea would be Ferguson's last game at Old Trafford, they were able to turn the occasion into a tribute to him. Ferguson went on to lift the Premier League trophy, traditionally the captain's privilege, after captain Nemanja Vidic and vice-captain Patrice Evra insisted he took it first.
The Scot said he had made his decision to quit at Christmas and after his plans became public knowledge last week, said: "This club is a sieve."
Ferguson's final match in charge of United will be Sunday's visit to West Bromwich Albion. Since his appointment in 1986, he has won 38 trophies, including 13 league titles.