Nine-time Grand Slam champion Monica Seles has revealed she was diagnosed with myasthenia gravis - a neuromuscular autoimmune disease - three years ago.
The 51-year-old has chosen to go public with the rare long-term condition, which causes muscle weakness, to raise awareness before this month's US Open.
Seles first noticed symptoms of the condition, which can affect most parts of the body - including the muscles that control the eyes, around five years ago.
"I would be playing [tennis] with some kids or family members, and I would miss a ball," former world number one Seles told The Associated Press.