Jonah Lomu's crippling kidney disease means he won't fight in boxing's Fight for Life next month.
The 36-year-old is on dialysis and the future of his transplanted kidney appears bleak.
At last night's IRB rugby awards ceremony in Auckland, Lomu said that he had withdrawn from the event.
Doctors at Auckland City Hospital have told the former All Black star there is only a slim chance his kidney will survive.
It is not yet clear whether he will have to return to the transplant list, but tests are being done to see if the failing kidney can be revived.