Tennis legend Novak Djokovic has opened up about a longstanding health issue he has been dealing with for years. At the Cincinnati Open, the Serbian, who holds the all-time men's record of 428 weeks as world No. 1 in singles, struggled physically throughout his second-round match.The 39-year-old was seen crouching on all fours between points, required a medical timeout and appeared to vomit into towels as extreme heat and humidity took a toll. The 24-time Grand Slam champion suffered a surprising second-round defeat, losing to Argentina's Thiago Agustín Tirante 2-6, 6-4, 6-4. What Health Issue Does Novak Djokovic Have? Following the defeat, Djokovic revealed that he has been dealing with a longstanding health condition that becomes particularly difficult to manage in hot and humid conditions. "It's because of a health issue I have," Djokovic told reporters after the match. "I've been dealing with it for many years now. It causes me a lot of problems, especially when there's a lot of humidity and heat." Djokovic said he had anticipated difficult conditions in Cincinnati, but the combination of heat, humidity, nerves and other factors ultimately made the situation worse during his match against Tirante. His physical struggles also raised questions about his future at the Cincinnati Open. Asked whether he planned to return to the tournament in 2027, Djokovic gave an uncertain response. "I certainly hope so, but unfortunately, at this point it seems more likely that I won't. However, we'll see what the future holds." Novak Djokovic's Previous Health Issues and Injuries Djokovic has dealt with several injuries and health challenges throughout his career. Respiratory issues: Before 2010, Djokovic faced heat exhaustion, breathing difficulties and physical collapses. He later changed his diet after identifying gluten and dairy intolerance. Elbow injury: Chronic right elbow problems led to surgery in 2018. Abdominal tear: He played through an abdominal tear to win the 2021 Australian Open. Hamstring injury: He battled a left hamstring injury during his 2023 Australian Open title run. Knee injury: A torn meniscus forced him to withdraw from the 2024 French Open. Djokovic on the Physical Demands of Ageing In 2023, Djokovic acknowledged that his body was beginning to feel the effects of a long career, although he still felt he had fuel left in the tank. "I am being completely honest with you guys. I have asked this question also, but it's not like I think about it all the time. The desire is still there, but things can change quickly – I am 36, I've been a pro for 20 years." He said he did not view age as a decisive factor, instead focusing on his overall physical condition and whether he continued to enjoy playing. Age can affect tennis performance through changes such as reduced muscle mass, slower recovery and lower aerobic capacity, which can also increase injury risk. However, modern sports science and tactics can help players remain competitive as they age. Research suggests that people who regularly play tennis may add nearly 10 years to their lives, potentially outperforming the longevity gains associated with several other sports. "Tennis is a sport that is unique because people of all ages play it, from age two to 92 or older, and that makes it accessible to a lot of people," Dr. Melissa Leber, director of emergency department sports medicine at Mount Sinai Health System, told the New York Post.