A world champion kickboxer has died from complications caused by COVID-19 just weeks after he discharged himself from the hospital. Frederic ‘The Undertaker’ Sinistra, 41, died at his home in Belgium earlier this month, according to local outlets. An unvaccinated heavyweight fighter, Sinistra refused to use the term COVID-19. His coach, Osman Yigin, said he’d forced the athlete into the hospital after he contracted the “little virus,” as Sinistra liked to call it. From inside an intensive care unit in Liège, Sinistra posted updates on social media, maintaining, “A warrior never abdicates!!!!!! I will come back even stronger,” even as he acknowledged the inflammation in his lungs was 33 times greater than a healthy level. He went home days later and reportedly began to treat himself with oxygen. His partner announced his death on his Facebook page on Dec. 16.