Fulham midfielder Kevin McDonald says he has chronic kidney disease and is due to have a transplant next month.
The 32-year-old Scot has lived with the condition for 12 years but it has deteriorated, and he accepts it may now end his career prematurely.
"Football has been great but this needs to take over," he told Fulham's website.
"I want to get it done now, make sure everything is right and come back from it and live a normal life again."
McDonald, who has been capped five times by Scotland, is hopeful of being able to continue playing professionally after the operation and a three-month recovery period, but while he has been sidelined with the condition this season he has been working with Fulham's Under-23 and Under-18 sides to develop his coaching skills.