UFC star Anderson Silva has been rushed to hospital and may require emergency gall bladder surgery.
Silva was due to headline UFC 198 in his native Brazil on Saturday but was taken ill before boarding the plane from Rio de Janeiro to Curitiba.
"He called me and said 'I'm going to the hospital, but I'll get better', so we came to Curitiba," Silva's coach Luiz Carlos Dorea said.
"When we arrived in Curitiba, he said 'Master, I came home but the pain is too much'. I told him to eat something, but he said 'I can't, I'm eating and throwing up'. He told me this afternoon [Tuesday] that it was too painful and he had to go back to the hospital."
Silva, who was aiming to return to winning ways after losing a controversial decision to Britain's Michael Bisping at London's O2 in February, was due to fight Uriah Hall in his first fight in Curitiba in more than a decade.
"He was doing great, and this came out of nowhere," Dorea said. "He felt some [abdominal] pain before, but nothing serious. He always came back to train the next day, so we never imagined it would be something like this."