
Monica Seles, the former world No. 1 tennis star and nine-time Grand Slam champion, has been diagnosed with myasthenia gravis, a rare neuromuscular autoimmune disease that causes muscle weakness and fatigue.
The 51-year-old, diagnosed three years ago, shared her condition in interviews to raise awareness ahead of the U.S. Open, aiming to support others facing similar health challenges.
"I was diagnosed with myasthenia gravis, and it’s been a challenging journey, but I’m managing it with the same determination I brought to the tennis court," Seles. "It took me quite some time to really absorb it, speak openly about it, because it's a difficult one. It affects my day-to-day life quite a lot," She told.
Seles, born in Yugoslavia and later a U.S. citizen, dominated women’s tennis in the early 1990s, winning eight Grand Slam titles by age 19, including three consecutive French Open titles (1990–1992) and four Australian Open titles. Her aggressive playing style and powerful groundstrokes made her a formidable rival to Steffi Graf. However, her career was derailed in 1993 when she was stabbed on court by a deranged fan during a match in Hamburg, Germany. The attack forced her out of the sport for over two years, and though she returned to win the 1996 Australian Open, she never fully regained her pre-injury dominance.
Reflecting on her tennis career, Seles said, "There’s so much joy in playing the sport," highlighting her continued passion for tennis despite past challenges. "I had to, in tennis terms, I guess, reset — hard reset — a few times," she told, describing her diagnosis as another "hard reset" in her life.
Myasthenia gravis (MG) disrupts communication between nerves and voluntary muscles, leading to symptoms such as drooping eyelids, double vision, and weakness in the arms, legs, or neck. Seles first noticed symptoms five years ago while playing tennis with children or family members, describing how she would "miss a ball" because she saw "two balls." She also struggled with routine tasks, noting that "even blowing out my hair became very difficult." The disease affects approximately 20 out of every 100,000 people worldwide, with an estimated 60,000 cases in the U.S. alone, though mild cases may go undiagnosed, according to the Cleveland Clinic.
The autoimmune form of MG occurs when the immune system mistakenly attacks acetylcholine receptors at the neuromuscular junction, impairing muscle contraction. The exact cause is unclear, but dysfunction in the thymus gland, which may contain abnormal immune cells, is often implicated, per the Cleveland Clinic.
MG is more common in women under 40 and men over 60 but can affect any age, including children, according to the National Institute of Neurological Disorders and Stroke (NINDS). Symptoms also include difficulty speaking, chewing, swallowing, or breathing, and while many complications are treatable, severe cases can be life-threatening, such as during a myasthenic crisis requiring ventilatory support.
It’s critical to note that MG diagnosis often involves neurological evaluation, blood tests for autoantibodies (e.g., anti-acetylcholine receptor antibodies), electromyography (EMG), and the edrophonium test, which temporarily improves muscle strength in MG patients. Seles was referred to a neurologist after experiencing double vision and limb weakness, highlighting the importance of early specialist consultation for accurate diagnosis.
Seles revealed she has been living with the condition for some time, managing it through treatment while maintaining an optimistic outlook. The disease, while chronic, can often be controlled with medication (e.g., cholinesterase inhibitors like pyridostigmine), immunosuppressive therapies, or thymus gland removal surgery. In some cases, MG may enter remission, either temporarily or permanently, with muscle weakness resolving completely, per NINDS. Lifestyle adjustments, such as pacing activities to avoid fatigue, are also key, as Seles emphasized in her interviews.
"It’s a marathon, not a sprint," Seles said, emphasizing her approach to coping with the disease. "You have to listen to your body and take it one day at a time."
Seles, who retired from professional tennis in 2008 and was inducted into the International Tennis Hall of Fame in 2009, has long been an advocate for mental health and now extends her advocacy to chronic illness. She continues to inspire through her role as a motivational speaker and her presence at tennis events, such as the Citi Taste of Tennis in Miami. Seles expressed a desire to raise awareness, stating, "I wished at the time of my diagnosis, I had somebody like me speak up about it." She hopes her openness will encourage patients to seek early diagnosis and treatment, which can significantly improve quality of life.
Her diagnosis adds to a history of overcoming adversity, including her recovery from the 1993 stabbing and struggles with binge eating disorder. "It gave me a strength that I don’t think anyone else could take away," Seles once said about her return to tennis post-injury. She described her journey with MG as learning to live a "new normal," likening it to previous life challenges like immigrating to the U.S. at 13 and navigating fame as a teenager.
Despite the challenges of myasthenia gravis, Seles remains committed to raising awareness and supporting others with the condition. She chose to speak publicly ahead of the U.S. Open, starting August 24, 2025, to highlight MG’s impact. Her story underscores the importance of patient education, early intervention, and multidisciplinary care involving neurologists, immunologists, and physical therapists to manage MG effectively.
"I’m still here, still fighting," Seles told the People. "That’s what I’ve always done, and that’s what I’ll keep doing."
(Rh/Eth/MKB/MSM/SE)