Severiano Ballesteros is in a serious condition in hospital after tests on his brain found evidence of a "grave illness", according to reports in Madrid.

The Spaniard, a former world No 1 and the winner of five major championships, was admitted to Laz Paz Hospital on Monday after fainting and briefly losing consciousness at Barajas Airport in Madrid.

The 51-year-old released a statement on his online blog yesterday in which he said he felt well and thanked fans for their messages of support, but the results of a scan have given cause for concern.

Ballesteros has regained consciousness and is able to talk but doctors were concerned enough to call his family to his bedside and are expected to issue a statement detailing his condition tomorrow.

The former Ryder Cup captain has suffered from health problems of late and spent a night in hospital last year after a heart scare. Doctors diagnosed an irregular heartbeat.

Ballesteros, who retired from competitive golf in 2007, called a press conference at last year's Open Championship at Carnoustie to scotch rumours that he had attempted suicide.

More news to follow.