London: Messages of support poured in for Alex Ferguson after the legendary former Manchester United manager had emergency surgery for a brain haemorrhage on Saturday.
News of his operation was made public by his old club, with a United statement cautiously optimistic about the 76-year-old's prospects.
"Sir Alex Ferguson has undergone emergency surgery today for a brain haemorrhage," the statement said.
"The procedure has gone very well but he needs a period of intensive care to optimise his recovery. His family request privacy in this matter."
According to the Daily Mail, an ambulance was called to the Scot's home in Cheadle, near Manchester, in northwest England at 9am local time (0800 GMT) on Saturday and took him to Macclesfield district hospital.
Ferguson, the most successful manager in British football history, was then, the Mail reported, subsequently transferred, with a police escort, to the Salford Royal hospital.
Concerns for Ferguson's health started to mount when it was announced that his son, Darren, the manager of English third tier club Doncaster, would miss his side's League One match against Wigan on Saturday because of "family reasons".
"It is tragic. I am going to find out how he is as soon as I possibly can," said Everton manager Sam Allardyce, a longstanding friend of Ferguson's, after his side's 1-1 Premier League draw at home to Southampton.
"Obviously I knew it was extremely serious when I knew his son Darren didn't attend his own game at Doncaster today," the former England boss added.
"I hope he is in good hands and I hope the operation is a major success because as a personal friend...I hope he has a full recovery."
Southampton manager Mark Hughes, who made his name in football as a United striker during the early years of Ferguson's time at Old Trafford, said: "I only just got a little whisper earlier on. I was hoping it wasn't true. I wish him all the best."
Other United players, past and present, took to social media to wish Ferguson a speedy recovery.
"Gutted to hear the news tonight about Sir Alex," tweeted United defender Ashley Young. "Don't really know what else to say other than thoughts and prayers with you and your family, Boss."
Young's thoughts were echoed by former United goalkeeper Peter Schmeichel, who said: "Please Be strong Win this one."
And the sympathy extended beyond the United 'family', with Manchester City captain Vincent Kompany, whose side recently won this season's Premier League, tweeting: "Hang in there Sir Alex. Thoughts are with the family and close ones."
Meanwhile ex-England striker turned BBC football presenter Gary Lineker said: "Very sorry to hear the news that Sir Alex Ferguson is seriously ill in hospital. Wish him all the very best."
Away from football, Nicola Sturgeon, the First Minister of Scotland, tweeted: "My thoughts are with Alex Ferguson and his family - wishing him a full and speedy recovery."
Ferguson retired five years ago when he stepped down as United manager, having won a staggering 38 major trophies in just over 26 years in charge, including 13 Premier League titles and two European Champions League triumphs during his time at Old Trafford.
He was back at United's home ground last week to present a commemorative vase to old rival Arsene Wenger, who steps down as Arsenal manager at the end of the season.
Prior to arriving at Old Trafford, Ferguson, a former striker with Glasgow giants Rangers, had enjoyed considerable managerial success in charge of Aberdeen, where his trophy haul included three Scottish championships, four Scottish Cups and the 1983 European Cup Winners' Cup.