Severiano „Seve” Ballesteros, a Spanish professional golfer and former World Number 1, will need to undergo brain surgery this Friday because his tumor, which is classified as an oligoastrocytoma (type that affects the cells protecting brain and spinal cord nerve cells) has turned out to be cancerous.

Three doctors from the La Paz Hospital in Madrid, Spain, will be performing the procedure that has been deemed as being highly complex: Javier Heredero, head of the hospital's neurosurgery unit, alongside neurosurgeons Marcelino Perez Alvarez and Alberto Isla.

Ballesteros’ brain surgery is scheduled to begin early Friday morning, doctors estimating it would last until the afternoon. The operation is aimed at removing what is left of a malignant tumor lodged deep in the golfer’s brain, in order to relieve the pressure that recent complications have given rise to, including swelling and bleeding.

On October 6, after he lost consciousness for a short time while at Madrid's international airport, Seve Ballesteros was hospitalized and underwent an operation called decompressive craniotomy, which entails the removal of a part of the skull, ten days later.

Ballesteros, 51, won five major tournaments between the years of 1979 and 1988, including The Masters (twice), which is one of four major championships in men's professional golf.

In 1999, he was inducted into the World Golf Hall of Fame, while one year later, he became the top golfer from Europe.

On July 16, 2007, he announced he was retiring from his career as a professional golfer, due to back problems that kept reoccurring.