The club posted a statement on Saturday evening confirming a haemorrhage was the cause:
Manchester United @ManUtd
Sir Alex Ferguson has undergone surgery today for a brain haemorrhage. The procedure has gone very well but he needs a period of intensive care to aid his recovery. His family request privacy in this matter. Everyone at Manchester United sends our very best wishes. https://t.co/SDoNzMwVEZ
A statement released by Rovers read:
"Rovers manager Darren Ferguson will not be at Saturday's game due to family reasons. Gavin Strachan will oversee the final game of the Sky Bet League One season in the manager's absence.
"Darren asks for privacy, and will provide an update through the club during the week."
Sky Sports News earlier reported the former Red Devils manager was in a "serious condition" ahead of undergoing surgery:
Ferguson, 76, is widely considered to be British football's best manager of all time.
Michael Carrick and David de Gea led the tributes after hearing of their former boss' condition:
Ferguson managed United for 26 years and won 38 trophies during his Old Trafford tenure, including a record 13 Premier League titles, five FA Cups and two UEFA Champions League winners' medals.
First Minister of Scotland Nicola Sturgeon reacted to news of his hospitalisation on Saturday:
Ferguson was recently at the Theatre of Dreams to watch his old club beat rivals Arsenal 2-1 in what was former managerial nemesis Arsene Wenger's final trip to Old Trafford.