Roy Keane: Joined Manchester United instead of Blackburn Rovers (1993)
When Nottingham Forest were relegated from the Premier League at the end of the 1992/93 seasons, Roy Keane was allowed to leave thanks to a clause in his contract that he had negotiated with the club. Keane was one of the hottest prospects at the time and Blackburn Rovers manager Kenny Dalglish wanted him to join the Lancashire club.
But mistakes in the paperwork saw the actual deal pushed by a week as the office was closed over the weekend. Nevertheless, Dalglish and Keane had a verbal agreement to complete the deal the following Monday.
That was when Sir Alex Ferguson got word of the delay in the transfer and personally phoned Keane to convince him to move to Old Trafford. The Scottish manager even had all the correct paperwork ready.
And so, while Blackburn dragged their feet over the transfer, United stepped in and signed Keane for a then-British record £3.75m.