MADRID - SEVE Ballesteros' state of health worsened on Thursday, the Spanish golf legend is undergoing fresh surgery to ease a build-up of fluid in the brain, the Madrid hospital treating him said.

The 51-year-old, who collected 87 titles before knee and back problems forced him to retire last year, underwent surgery on Tuesday to remove a brain tumour.

'Forty-eight hours after his operation, the patient Severiano Ballesteros suffered a loss of consciousness because of a cerebral oedema and had to undergo a decompressive craniectomy,' La Paz Hospital said in a statement.

'His situation is stable and is under control.'

A decompressive craniectomy is a medical procedure aimed at relieving critically increased intracranial pressure.

Spain's world number one tennis player Rafael Nadal, meanwhile, praised Ballesteros, describing him as one of the greatest Spanish sportsmen of all time.

'I have been in touch with his family and I told them that they have my support and good wishes,' said world number one Nadal who was speaking at the Madrid Masters tournament where he reached the quarter-finals on Thursday.

'He has proved to be a very strong man all his life; we know he is one of the great Spanish sportsmen.

'He was the best Spanish golfer ever so I just want to send him all my support and strength. It looks like the operation went well, let's hope everything goes smoothly.'

Ballesteros was taken to La Paz Hospital on October 6 after he collapsed and briefly lost consciousness at Madrid airport.

He announced on Sunday he had been diagnosed with a brain tumour and would undergo a biopsy before doctors decide on a course of treatment.

Ballesteros won the British Open in 1979, 1984 and 1988 and became the first European to win the Augusta Masters in 1980, a title he repeated in 1983.

He was an influential figure in the Ryder Cup, winning 20 points from 37 matches and captaining Europe to victory at Valderrama in 1997.

Known for his flamboyant and imaginative style of play, he won one of his three British Open titles by playing a shot from a temporary parking lot. -- AFP