MADRID, Spain (AP) -- Five-time major winner Seve Ballesteros has undergone surgery to remove part of his brain tumor.

A spokeswoman at La Paz hospital said a sizable part of the Spaniard's tumor was removed during Tuesday's operation, which took 12 hours, according to Spanish state news agency Efe.
The removed tumor is to be analyzed and it will take several days before results are known.
"At the moment he is conscious and stable, although he will not be able to receive any visitors in the coming days until he has recovered from the surgical process," the hospital said Wednesday in a statement.
The hospital said Ballesteros had been moved to a post-operation room in the intensive care unit. It said there would be no more news about the golfer until he changes ward, most likely next week.
The 51-year-old Ballesteros briefly lost consciousness and was admitted Oct. 6 to the hospital, where his tumor was discovered.
On Monday, Ballesteros issued a statement acknowledging he had a tumor and saying he faced "the hardest challenge of my life."
Ballesteros, who won a record 50 tournament on the European Tour, captured the British Open three times and the Masters twice before retiring last year due to a long history of back pain. He has since focused mostly on golf course design.
Many credit Ballesteros for transforming the European game.
When the Ryder Cup was expanded to include continental Europe in 1979, Ballesteros helped beat the United States in 1985 to begin two decades of dominance. He also captained Europe to victory in 1997 at Valderrama, Spain.
Ballesteros and Jose Maria Olazabal of Spain are the most formidable partnership in Ryder Cup history, with 11 wins, two losses and two halves.