The 76-year-old was rushed to hospital over the weekend and went under the knife to treat a brain haemorrhage.
United confirmed as much on Saturday evening, urging well-wishers to respect the privacy of the Ferguson family.
Since then, tributes have piled in for the Scot as we awaited positive news on his recovery.
Speaking to 'the Telegraph', renowned neurosurgeon Dr Peter Hamyln gave his take on the potential cause of the problem and how to optimise Sir Alex's recovery.
“The most common form (of haemorrhage) for a man of his age with a history of cardiovascular issues is intracerebral, in which there is bleeding within the brain tissue, causing irreparable damage to those cells," he explained.
“In Sir Alex’s case, his surgeons have decided to operate almost certainly because they felt the size of the blood clot was causing damage to the remaining brain tissue. This is often life-saving surgery and aims to reduce any long-term disability Sir Alex might suffer with this form of stroke.
“For the first few days after the operation, the focus is on the patient’s life support. A prognosis is very hard to give in the first days and often for some weeks.
“If they survive without signs of improvement after several months, then it is unlikely that an individual will return to their former health. However, in the immediate aftermath there is everything to fight for and the potential for a full recovery, albeit sometimes after a long period of rehabilitation.”
At the moment, Ferguson remains in intensive care, though it has been widely reported that the procedure went perfectly.