Sonny Bill Williams challenged to swimming race

Sonny Bill Williams has been challenged to a swimming race by an unlikely contender - an eight-year-old boy from Auckland.

Sam Howarth filmed his video challenge to the sporting star earlier this week.

"He is a bit of a keen swimmer and he is just a massive fan of Sonny," said Sam's mother Kelly Howarth.

The video was shot at Northern Arena fitness centre, where Mrs Howarth works.

Sam has been swimming since he was six-years-old and has opened the challenge up to freestyle, backstroke or breaststroke - Williams' choice.

"Sonny is flattered by the offer but is obviously a bit busy this weekend. We all hope Sam enjoys the game," said Kiwis manager Tony Iro.

Williams is currently England for this weekend's game World Cup final.