Forget doctor’s orders. Vitor Belfort was determined to make his final walk to the Octagon.

Sources confirmed with MMA Fighting’s Guilherme Cruz that “The Phenom” suffered an injury to his left knee in the first week of camp preparing for UFC 224, which took place last Saturday at the Jeunesse Arena in his home city of Rio de Janeiro.

News of the injury was first reported by Combate.

Belfort, 41, would go on to lose by second-round knockout to fellow Brazilian star Lyoto Machida. Afterwards, the former UFC light heavyweight champion laid his gloves down in the Octagon and declared his retirement, as was expected, signaling the end of an MMA career that began in 1996.

Sources told Cruz that Belfort was advised by multiple doctors to pull out, but he made the call to fight despite being injured. It is still being decided whether he will undergo surgery on his knee.

UPDATE: Belfort wrote a post on Instagram to address the injury.