Ballesteros, 51, underwent 12 hours of surgery Tuesday at a hospital in Madrid, Efe, the Spanish state news agency, reported. At least part of the tumor was removed during the procedure, hospital officials said
Officials at La Paz Hospital released a statement saying Ballesteros is "now conscious and in stable condition but may not receive visitors in the coming days until he has recovered from the surgical process."
Ballesteros collapsed Oct. 6 at a Madrid airport and subsequent examinations indicated a brain tumor. On his Web site in a message dated Sunday, Ballesteros confirmed the existence of the tumor and said, "I want to be the best facing the most difficult match of my life."
Ballesteros won the British Open three times and the Masters twice. His 50 European Tour victories top the all-time list there and he had 87 total tournament victories. He was inducted into the World Golf Hall of Fame in 1999.