Social media continued to be awash with tributes and get-well messages for the 76-year-old Ferguson, who was in intensive care late Saturday according to a statement from United.
An ambulance was reportedly called to his Cheshire home at 9am yesterday, before he was taken to Macclesfield District Hospital.
Ferguson was due to be in the dugout at the Keepmoat Stadium but a Rovers statement read: "Darren asks for privacy, and will provide an update through the club during the week".
In a later tweet, the club also wished Ferguson a "comfortable, speedy recovery". "As a personal friend, I hope he has a full recovery".
Former United striker Mark Hughes, speaking after his Southampton side's draw with Everton, said: "I wish him all the best".
Careful not to offer public opinion on the mixed fortunes of the club he left as league champions, he keeps in contact with nearly all of his former players, asking them how they and their teams are playing and how their families are doing. "Sending prayers and love to Cathy and the whole family x @manchesterunited".
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He also helped to made households names of two of the game's biggest stars: David Beckham and Cristiano Ronaldo. Be strong Boss. Raimond and Marita.
When Ferguson announced his retirement, Beckham said in an interview with Sky Sports that his former boss meant "everything" to Manchester United. Thoughts with all the family at this sad time.
He tweeted: "Praying for The Boss that he makes a full recovery from his Brain Haemorrhage".
FC Barcelona too wishes a speedy recovery for Sir Alex.
Another added: "Very classy Tony much respect, great performance I hope you get what you want in the future". "Edwin & Annemarie", said the couple's Twitter post.
Peter Schmeichel: Please. Be strong.
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Manchester United captain Michael Carrick said he was "absolutely devastated", while goalkeeper David De Gea said he was praying for his former manager. "Thoughts are with the family and close ones".
Ferguson stepped down in 2013 after winning 38 trophies, including 13 league titles and two Champions Leagues during his time at Manchester United, which he had managed since 1986.
Ferguson was recently seen for the United clash with Arsenal at Old Trafford when he presented departing Arsenal boss Arsene Wenger some end-of-season silverware.
In 2001 he chose to leave the following year but was persuaded by his family to change his mind and stayed on until 2013.
But the death of his wife's twin sister in 2012 provided Ferguson with what he later wrote was a "watershed moment".
Ferguson retired from his Man U managerial role in 2013.
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