Tennis great Monica Seles is speaking out about her battle with myasthenia gravis, a rare autoimmune disease that weakens muscles. The 51-year-old, who won nine Grand Slam titles and was inducted into the International Tennis Hall of Fame,

Nine-time grand slam champion Monica Seles has revealed that she was diagnosed with myasthenia gravis — a neuromuscular autoimmune disease — in a recent interview with The Associated Press.