Tributes have poured in for Anthony "Rumble" Johnson, after the former UFC title challenger’s death was announced early on Monday. Bellator MMA, the promotion Johnson most recently competed in, confirmed the news on social media, with a company spokesman later saying the 38-year-old American had been battling illness for more than a year. “The Bellator family is devastated by his untimely passing and we send our condolences to his family and friends during this difficult time,” the announcement said. According to Yahoo! Sports, Johnson died from organ failure because of non-Hodgkin’s lymphoma and hemophagocytic lymphohistiocytosis, a rare disorder of the immune system. Johnson, a light-heavyweight who went 23-6 in his professional MMA career, last competed in May last year. The following September, he posted on<a href="https://www.instagram.com/p/CT-Jf7TFLJO/?utm_source=ig_embed&ig_rid=8e0ef2a8-5db8-49eb-a701-3c7b3bdf72c4"> </a>Instagram that he needed "as many prayers as I can get" and was in a battle, noting it was "not Covid". On May 17, Johnson posted on Instagram that he had gotten good news from his doctor, saying there were "big improvements". But in late October, Johnson's manager told ESPN that Johnson was "going through some health problems right now ... he's not doing well". Johnson fought in the UFC from 2007 to 2017, losing twice to Daniel Cormier in light-heavyweight title bouts. Johnson competed in three weight classes for the promotion and established a reputation as a powerful puncher and a fan favourite for his aggressive, striking-based approach in MMA. He retired in 2017 from the UFC after his second title loss to Cormier, but returned to competition with Bellator for one bout in 2021 before his health problems worsened. Reacting to the news early on Monday, Cormier tweeted: "Rest easy my brother. For a guy who struck fear in so many peoples heart Anthony Johnson was a caring person. From random text to check ins during loss. What a person he was, Rumble will be missed. Sometimes life doesn’t seem fair. Horrible news.” Glover Teixeira, the recent light-heavyweight champion, said on social media: “I am so sad to hear about this news. One of the most scary & tough opponents that I had ever faced and one of the nicest and most humble humans I have ever met. My heart is broken. My condolences to his family. RIP.” Former UFC middleweight champion Michael Bisping posted on Twitter: “Utterly shocked and saddened by this. RIP. Sincere condolences to all his family and loved ones.” Michael Chiesa, UFC welterweight, added his condolences, tweeting: “RIP Anthony “Rumble” Johnson. One of the most prolific KO artists our sport has ever seen. My prayers go out to his family and everyone affected by this tragedy.”