Seve Ballesteros is in a stable condition in intensive care after undergoing a seven hour operation to remove a brain tumour detected last week.
The 51 year old now awaits the results of a biopsy before doctors can decide what course of treatment the Spaniard requires.
Ballesteros collapsed at Madrid airport last Monday and was taken to hospital in the city, where his family have been keeping a bedside vigil.
A statement from La Paz Hospital said: "The patient will spend a post-operative period in the intensive care unit.
"He is currently conscious and in a stable condition, although he cannot receive visits in the coming days until he recovers from the surgery."
A statement released by The Ryder Cup winning Captain on Sunday thanked people for their messages of support and said he would face the “most difficult match of his life” with all of his strength.
Speaking on behalf of his fellow Board Members, The European Tour’s Executive Management and all staff, Neil Coles, Chairman of The PGA European Tour Board of Directors, said: “We are confident that Seve will conquer this challenge with the same determination he has brought to all previous challenges.”
News of Seve's operation reached the Portugal Masters, where players including Order of Merit top two Robert Karlsson and Lee Westwood and defending champion Steve Webster all sent their best wishes to the popular Spaniard.
Westwood said: "He's always been a battler and hopefully he can use those battling qualities in this fight to regain fitness and health."
