Severiano Ballesteros has confirmed that he has been diagnosed with a brain tumour.
The five-time major winner has been in Madrid's La Paz hospital since Monday after briefly losing consciousness at Barajas airport on the same day.
The Spaniard was kept in intensive care until Saturday as doctors carried out a series of tests to ascertain his condition.
With his illness now diagnosed, Ballesteros made an announcement on Sunday having first informed his family.
"Throughout my entire career I have been one of the best at overcoming obstacles on the golf course. And now I want to be the best, facing the most difficult game of my life, using all my strength and also counting on those who have been sending me get-well messages," read the statement.
"Now I've been able to tell my three children personally and their mother, now I can tell you the illness that I am suffering from. After the exhaustive tests that I have undertaken in the Hospital La Paz (Madrid) they have detected a brain tumour.
"I have always sympathised with those people who face illnesses. Therefore, I want to remind them that with bravery, faith, serenity, confidence and a lot of mental strength, we have to face any situation no matter how difficult it is.
"Now my wish is to ask for respect for my family and especially for my children. We will keep you informed.
"I want to thank from the bottom of my heart all those people who have shown affection and interest in my state of health, with all kinds of support. Many thanks."
The statement also revealed that Ballesteros would undergo a biopsy on Tuesday with the Spaniard adding: "The doctors will now decide how to proceed."
Ballesteros is one of the most influential figures in the history of European golf having won the Open three times and Masters twice during a decorated playing career.
He also compiled an impressive Ryder Cup record, winning 20 points in eight appearances as a player and captaining Europe to victory at Valderrama in 1997.
He collected 87 titles worldwide before knee and back problems forced him to retire in 2007.