Williams goes over for a try against Great Britain last week

The 19-year-old picked up the injury during the Canterbury Bulldogs' run to last month's Grand Final.

He underwent an MRI scan last week and has been pulled out of Saturday's match in Hull at his club's request.

But scrum-half Thomas Leuluai is expected to be fit after recovering from a shoulder injury.

Williams made his Test debut as an 18-year-old in the Anzac match in April and appeared in all three of the Kiwis' Tri-Nations fixtures so far.

He was man of the match in the Kiwis' opening 16-16 draw with Australia.

But Kiwis coach Daniel Anderson is backing the decision not to force him into their match against Great Britain.

"For his long-term future, I think it's the best decision," Anderson said.

Leuluai, another of the Kiwis' 19-year-olds, is likely to play at the KC Stadium.

He came off with a shoulder injury midway through the second half of the 22-12 defeat by Britain in Huddersfield nine days ago then sat out last week's 24-20 win over France.

But Anderson said: "We'll monitor him as the week goes on. We're still confident he'll play in the game."