"The operation went better than expected and Seve will now be under close observation for 48 hours in the intensive care unit," the hospital said.
Ballesteros was admitted to the hospital Oct. 6 after briefly losing consciousness at Madrid's international airport. Eight days later, a sizable part of the tumor was taken out.
This operation was described as one "of great complexity." Doctors wanted to relieve pressure on the brain caused by swelling and bleeding and remove remaining parts of the malignant tumor located in a very deep part of the brain.
"Today we remember Seve Ballesteros with special affection and concern," Crown Prince Felipe said Friday at an award ceremony in Asturias. "As he himself said, he is playing the game of his life at the moment."
Ballesteros' tumor is an oligoastrocytoma, which affects cells that cover and protect the nerve cells in the brain and spinal cord. In an earlier operation, part of his skull was removed to allow room for the swelling brain to expand.
Ballesteros won the British Open three times and the Masters twice. He captured a record 50 tournaments on the European tour before retiring last year because of a long history of back pain. He has since concentrated on golf course design.
Ballesteros revolutionized European golf. After the Ryder Cup was expanded to include continental Europe in 1979, he helped beat the United States in 1985 to begin two decades of dominance. He also captained Europe to victory in 1997 and teamed with Jose Maria Olazabal in one of the most formidable partnerships in Ryder Cup history.