Rory McIlroy could miss next week's season-ending event in Thailand after a bout of dengue fever.
The illness, which affects the blood cell count, is commonly caused by a mosquito bite.
"It could have been a number of things and I'm going to see a doctor again tomorrow before deciding whether to go to Thailand next week," said McIlroy.
"To be honest, I'm ready for the season to be done and looking forward to putting the clubs away."
The Northern Irishman is currently battling Luke Donald in Dubai for the number one spot.
