A united statement stated the process "had gone very well" however ferguson "wishes a period of intensive care to optimise his restoration".
The scot, seventy six, retired as united supervisor in might also 2013 after triumphing 38 trophies at some point of 26 years in price.
He became at antique trafford remaining sunday whilst he offered arsenal boss arsene wenger with a commemorative trophy.
Ferguson's circle of relatives have requested privacy as he recovers in salford royal sanatorium.
"we will maintain sir alex and his cherished ones in our mind at some point of this time, and we're united in our wish to see him make a relaxed, rapid healing," united later said in a tweet.
The most successful supervisor inside the history of the british recreation, ferguson's trophy haul at antique trafford protected 13 greatest league titles, two champions league crowns, 5 fa cups and 4 league cups.
Ferguson famously gained the treble of most useful league, fa cup and champions league in 1999, the year in which he became knighted.
United's club captain michael carrick said he turned into "devastated" to research his former supervisor had needed emergency surgical treatment.
"all my mind and prayers are with him and his circle of relatives. Be robust boss," he wrote on twitter.
Ferguson has been married to wife cathy given that 1966. His son darren manages doncaster rovers however did now not now not take fee in their league one in shape in opposition to wigan on saturday.
Arsene wenger and sir alex ferguson
Sir alex ferguson and arsene wenger pictured at old trafford final sunday
Ferguson commenced his playing profession with scottish membership queen's park as a 16-12 months-antique striker even as operating as an apprentice tool-employee at clyde shipyards.
His most brilliant spell as a participant came in a two-12 months stint at rangers from 1967. He retired as a player in 1974 when he turned into on ayr united's books.
He commenced his managerial career as a 32-yr-old at east stirlingshire before going to st mirren, where he won his first trophy by taking the scottish first division identify in 1977.
Ferguson moved directly to aberdeen and turned them into a chief force in a scottish top division wherein rangers and celtic had dominated.
He led them to 3 scottish titles, four scottish fa cups, one league cup and the ecu cup winners' cup in 1983 by using beating actual madrid 2-1 in the final.
Sir alex ferguson's man utd trophies
Ultimate league: 1993, 1994, 1996, 1997, 1999, 2000, 2001, 2003, 2007, 2008, 2009, 2011, 2013 fa charity/network shield: 1990 (shared), 1993, 1994, 1996, 1997, 2003, 2007, 2008, 2010, 2011
Fa cup: 1990, 1994, 1996, 1999, 2004 uefa notable cup: 1992
League cup: 1992, 2006, 2009, 2010 inter-continental cup: 1999
Champions league: 1999, 2008 fifa club international cup: 2008
Cup winners cup: 1991
Ferguson controlled scotland in the 1986 world cup in mexico following the dying of jock stein, although he turned into not able to take his usa beyond the organization level.
He became manchester united manager later that year.
United celebrated their first most fulfilling league triumph under ferguson in 1993, the club's first league identify for 26 years.
Willie miller, who served as aberdeen captain under ferguson, said he was "staggered" to listen the information.
"my mind are with the boss, cathy and the lads. Hoping the fantastic man does what he does nice and wins this assignment," he introduced.
Everton manager sam allardyce said: "i'm hoping he is in correct palms and that i hope the operation is a chief success. As a private friend, i hope he has a full recovery."
Sir alex ferguson and david beckham
David beckham posted this picture of himself as a kids player alongside sir alex ferguson
Cristiano ronaldo with sir alex ferguson
Cristiano ronaldo published a image of himself and sir alex ferguson throughout his time at manchester united
'maintain combating boss' - reaction from the football global
Former manchester united midfielder david beckham: hold preventing boss. Sending prayers and love to cathy and the whole circle of relatives.
Mike phelan, who became ferguson's assistant for 5 years: you've received more than most and if every person can, you may boss.
United defender ashley younger: gutted to listen the information this night approximately sir alex. Do not really realize what else to mention other than mind and prayers with you and your family, boss.
Former united goalkeeper edwin van der sar: devastated approximately the information approximately sir alex and knowing all too well approximately the situation ourselves. Live robust and hope collectively with all people you recover.
United defender chris smalling: gutted to listen the news about sir alex. Live sturdy boss. Mind are with you and your own family.
Former england striker and fit of the day host gary lineker: very sorry to listen the news that sir alex ferguson is critically unwell in sanatorium. Want him all the very fine.
Aberdeen fc: the thoughts and prayers of all people linked with aberdeen football membership are with our former manager sir alex ferguson and his own family following this night's news.
Liverpool fc: a wonderful rival but also a exquisite pal who supported this club at some stage in its most hard time, it is was hoping that sir alex will make a full restoration.
Manchester town: each person at manchester metropolis desires sir alex ferguson a full and rapid healing after his surgical procedure.
World football governing frame fifa: we join many across the world of soccer in sending our first-class wishes to sir alex ferguson.
