World Cup-winning rugby player Sonny Bill Williams concedes he'll have to make adjustments fighting an opponent the same size as himself for the first time.
Williams has confirmed his next bout, against Auckland's Richard Tutaki for the vacant New Zealand heavyweight title in Hamilton next February.
The 26-year-old Williams is allowed a certain number of fights under his New Zealand Rugby Union contract.
Tutaki, known as "The Tutaki Express Train", is a 10-year professional boasting a 19 win-21 loss record, with one draw.
Standing at 1.92 metres, Tutaki is a centimetre taller than Williams, while his rating on the respected Boxing Record Archive rankings is 288, five places higher than the All Black.
Williams is backing his fitness and speed to get him through the bout.
The fight will take place just two and a half weeks before his new Chiefs franchise open their Super Rugby season.