United confirmed on Saturday that Ferguson, 76, fell ill on Friday and has been in intensive care after undergoing a procedure which went "very well", according to the club.
Manchester City manager Pep Guardiola also sent his close friend his well wishes, revealing Ferguson had recently taken him out for dinner to congratulate him on winning the Premier League title with City. Amid countless messages of goodwill, not only from legends of the game, Aberdeen and United supporters, but fans around the world, including United's greatest rivals, football wishes Britain's most successful manager well and hopes to see him make a full recovery. He's the most important person in a lot of years.
Arsenal player Mesut Ozil posted to Twitter in support of Sir Alex, as did former Chelsea striker Didier Drogba.
Well wishes flooded in from former and current United players with other well wishers. Juventus coach Massimiliano Allegri, who is on the verge of leading the Turin giants to a seventh successive Serie A crown, said: "Stay strong Alex Ferguson".
Premier League chief executive Richard Scudamore is not surprised by the amount of well wishes Ferguson is receiving. Thoughts are with his wife Cathy and of course all the Manchetser United family.
It's that the players who played under Alex Ferguson at Manchester United have a respect and love for him that goes well beyond football. "Be strong, Boss!" he said. "I hope he has a full recovery". Keep fighting Boss, you've always done.
Manchester City fans display touching banner in show of support for Sir Alex Ferguson
Sky Sports News reporter James Cooper has been at the Manchester hospital throughout Sunday but he is not expecting an update on Ferguson's condition in the short-term.
Since benefitting from United soon after almost 27 years in control in 2013, the 76-year-old Ferguson has lasted to wait matches in Old Trafford, engage in training initiatives, also has turned into a routine in horse-racing as a dominant proprietor.
He won three Scottish Premier Division titles, four Scottish Cups, a Scottish League Cup.
Edwin van der Sar: Devastated about the news about Sir Alex and knowing all too well about the situation ourselves.
Ashley Young: Gutted to hear the news tonight about Sir Alex.
SIR ALEX FERGUSON was one of the greatest managers in English football history - but who were his best and worst signings?
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