Monica Seles first noticed the symptoms of myasthenia gravis — a neuromuscular autoimmune disease — while she was swinging a racket the way she’d done so many times.

Nine-time Grand Slam champion Monica Seles is battling a new challenge: a neuromuscular autoimmune disease called myasthenia gravis.

Tennis Icon Monica Seles, 51, Reveals Health Struggle Fans Never Knew About originally appeared on Parade. Tennis champion Monica Seles, 51, has revealed a difficult medical condition she has been dealing with for some time. On August 12, The Associated Press shared details about Seles' journey with a condition called myasthenia gravis.