Monica Seles, the nine-time Grand Slam tennis champion and International Tennis Hall of Famer, has stepped forward to share a deeply personal chapter of her life—her diagnosis with myasthenia gravis (MG), a rare and often misunderstood neuromuscular autoimmune disease. Speaking publicly for the first time about her condition on August 12, 2025, Seles, now 51, hopes her story will shine a spotlight on MG, offering support and awareness for others grappling with the disease.
According to Good Morning America and the Associated Press, Seles first noticed her symptoms three years ago. As a professional athlete, she was intimately attuned to her body, so when she began experiencing extreme leg and arm weakness, along with double vision, she immediately sensed something was amiss. "I started experiencing these symptoms of extreme leg weakness, arm weakness, double vision. So I realized, 'This is very unusual,'" Seles recalled in her interview with Good Morning America. The changes were jarring for someone whose body had been her instrument for decades.
Her journey to a diagnosis wasn’t straightforward. Seles described missing balls while casually playing tennis with family or children—a startling development for a former world number one. "I would be playing with some kids or family members, and I would miss a ball. I was like, 'Yeah, I see two balls.' These are obviously symptoms that you can't ignore," she told the Associated Press. Even everyday tasks, like blowing out her hair, became challenging. It was only after seeing a doctor and being referred to a neurologist that she was diagnosed with myasthenia gravis.
MG, as explained by the National Institute of Neurological Disorders and Stroke and cited by ABC News, is a chronic neuromuscular disease that causes weakness in voluntary muscles—those responsible for moving the arms and legs, as well as essential functions like breathing, swallowing, and facial movements. The Cleveland Clinic estimates that about 20 out of every 100,000 people worldwide are affected, with roughly 60,000 cases in the United States at any given time. The actual number may be higher, as mild cases sometimes go undiagnosed.
Symptoms can vary widely but often include muscle weakness and fatigue, droopy eyelids, blurry or double vision, limited facial expressions, difficulty speaking, swallowing, or chewing, and trouble walking. Seles experienced many of these firsthand. "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 admitted to the Associated Press. In severe cases, MG can lead to a myasthenic crisis, where the muscles controlling breathing are affected, requiring immediate medical intervention. These crises are triggered by infection, stress, or medications and occur in approximately 15-20% of individuals with MG.
The disease is autoimmune in nature, meaning the body’s immune system mistakenly attacks healthy cells. While the exact cause remains unclear, studies suggest a malfunction in certain immune cells within the thymus gland. Although MG can strike at any age, it most commonly affects women under 40 and men over 60, but, as Seles’s experience demonstrates, it can appear in anyone.
Diagnosis typically involves a combination of physical and neurological examinations, blood tests, and advanced electrodiagnostic techniques. While there is currently no cure, a variety of treatments can help manage symptoms and improve muscle strength. These include medications, surgery to remove the thymus gland, and lifestyle modifications. "Once I was diagnosed, it was like a relief, but also it was a challenge. Even coming here today—in the old days, traveling would be a no-brainer. Now I had to get packing tips. I had to learn a new way to live with MG," Seles told Good Morning America.
In her new role as a spokesperson for Argenx, the pharmaceutical company behind one of her medications, Seles is also championing the Go for Greater campaign to raise awareness and encourage others to advocate for themselves. "When I got diagnosed with myasthenia gravis, I had no clue what it was. I had a hard time pronouncing it," she confessed. Her hope is that by speaking out, she can help others recognize symptoms earlier and feel less isolated. "I wish I had somebody like me speak up about it," she said, underscoring the importance of community and support.
Seles’s openness comes at a poignant time, just ahead of the U.S. Open tennis tournament, which begins August 24, 2025. Her connection to the event runs deep. Thirty years ago, she made a triumphant return to the U.S. Open after surviving a stabbing attack in Hamburg, Germany—a moment she describes as another major "reset" in her life. "The way they welcomed me... after my stabbing, I will never forget," Seles told the Associated Press. Now, as she adapts to her "new normal," she draws parallels between her current health journey and the many resets she’s faced throughout her storied career.
"I had to, in tennis terms, I guess, reset—hard reset—a few times. I call my first hard reset when I came to the U.S. as a young 13-year-old [from Yugoslavia]. Didn’t speak the language; left my family. It’s a very tough time. Then, obviously, becoming a great player, it’s a reset, too, because the fame, money, the attention, changes everything, and it’s hard as a 16-year-old to deal with all that. Then obviously my stabbing—I had to do a huge reset. And then, really, being diagnosed with myasthenia gravis: another reset. But one thing, as I tell kids that I mentor: 'You’ve got to always adjust. That ball is bouncing, and you’ve just got to adjust.' And that’s what I’m doing now," she reflected in her interview with the Associated Press.
Despite the challenges, Seles remains optimistic and encourages others to do the same. "Knowing that there’s hope out there... and a great community... has helped me tremendously," she shared with Good Morning America. Her advice is simple but powerful: "Advocate for yourself and know your symptoms." By sharing her experience, Seles hopes to foster greater understanding of myasthenia gravis, inspire others to seek answers, and remind everyone that even champions must sometimes learn to adapt in unexpected ways.
Seles’s courage in confronting her diagnosis publicly not only raises the profile of a little-known disease but also serves as a testament to resilience—a quality she’s demonstrated both on and off the court.
