Ketlen Vieira badly missed weight for the PFL Tampa main event against women's featherweight champion Cris Cyborg.
Vieira, a former UFC women's bantamweight contender, weighed in at 152.2 pounds Friday, 7.2 pounds over the divisional limit for title fights.
If Vieira beats Cyborg, the women's featherweight title will become vacant, Cyborg said in a post on X.
Vieira told MMA Fighting's Guilherme Cruz that a sudden illness caused the weight miss.
"I had severe pain in my kidneys and stomach since last night," Vieira said. "I felt really sick throughout the entire night. ... This morning, I felt sick again and had another severe episode. I can't explain why this happened.
"I was doing well on weight. I'm a bantamweight fighter, and it had nothing to do with my weight. I was in a lot of pain, and (my coach) wouldn't let me continue losing weight."
Vieira signed with the PFL in June and is scheduled to make her debut against Cyborg. She spent a decade in the UFC, putting together a 10-5 record and beating the likes of Holly Holm and Miesha Tate.
Cyborg, one of the greatest women's fighters in MMA history, is seeking her second PFL title defense after submitting Sara Collins in December. Saturday's main event is being promoted as Cyborg's retirement fight, though the 41-year-old Brazilian said earlier this week she's unsure whether she'll hang up her gloves.
