Seve Ballesteros underwent further surgery today after his condition deteriorated following an operation to remove a brain tumour.
The Spanish golf legend was recovering from surgery he had to remove the tumour on Tuesday when doctors took the decision to operate again.
The procedure was needed to reduce pressure on Ballesteros' brain.
A statement from the LA Paz hospital in Madrid read: "The patient is stable and remains under observation in the intensive care unit having undergone a decompressive craniectomy after suffering from a decrease in the level of consciousness due to a cerebral edema."
Ballesteros was taken to the hospital on 6 October after he collapsed and briefly lost consciousness at Madrid airport.
The 51-year-old announced on Sunday that he had been diagnosed with a brain tumour.
Ballesteros won the British Open in 1979, 1984 and 1988 and became the first European to win the US Masters in 1980, a title he claimed again in 1983.