(CNN) -- Golf legend Seve Ballesteros has undergone an operation in Madrid to remove a brain tumor, Spanish doctors confirmed in a statement on Wednesday.
Ballesteros, 51, who was admitted to La Paz hospital last week after collapsing, is now "conscious" and in a "stable" condition after Tuesday's 12-hour operation operation.
"Patient Severiano Ballesteros was surgically operated on yesterday by the medical team from the Neurosurgery Unit of La Paz Hospital," said the statement.
"The intervention, programmed to remove the brain tumor detected, started at nine in the morning and concluded without complications.
"The patient will go to the post surgical section of the intensive care ward," the statement continued.
"At this time he is conscious and his situation is stable, although he cannot receive visitors in the coming days until he recovers from the process.
"The next medical report from the hospital will be given when the patient has moved to a regular ward, which might occur next week."
A cancer specialist, speaking to CNN on condition of anonymity because he was not part of the medical team, said that doctors will now spend several days analyzing the tumor to determine just how serious the situation is and what treatment Ballesteros will require.
"They will be looking at, among other things, how aggressively the tumor has been growing," the specialist said. "That information and other factors they determine from analysis will allow them to come up with a plan for the next phase."
La Paz has not said how long Tuesday's operation lasted or when it will know whether the tumor is benign or malignant.
Five-time major winner Ballesteros, in a statement before the operation, called fighting his condition the "hardest challenge" of his life.
"Throughout my career I have been among the best at overcoming challenges on the golf course," he said. "Now I want to be the best confronting the hardest challenge of my life, with all my strength."
Ballesteros was also admitted to a hospital last year, when doctors discovered an irregular heartbeat.
The golfing world has rallied round to offer its support to a player who revolutionized European golf with his flamboyant play.
Ryder Cup partner Jose Maria Olazabal, who visited Ballesteros in hospital before Tuesday's operation, said he was "confident" he would recover, adding: "While I'm rightly worried, I thought Seve seemed very well. We were talking for a good while. I wish him a speedy recovery."
Fellow Spanish golfer Miguel Angel Jimenez added: "Seve, we love you. We all hope you recover as soon as possible and we're waiting for you."
Ballesteros, who won a record 50 times on the European tour, won the British Open three times and the U.S. Masters twice before retiring last year after battling back problems.
He burst to prominence by winning the 1979 British Open at Royal Lytham, captained Europe to Ryder Cup success over the United States at Valderrama in 1997.
Madrid Bureau Chief Al Goodman contributed to this report