Williams has had to be a spectator for a lot of NRL games

The 20-year-old will miss the start of the new NRL season with the injury.

Williams has been badly hit by a series of injuries to his knee, ankle and shoulder in recent seasons.

"I feel for him - he was shattered when we got the results but he's training again and doing everything he's allowed to do," said club doctor Hugh Hazard.

Feature: Williams has world at his feet

The loose forward was voted international newcomer of the year for his superb displays in the 2004 Tri-Nations, but missed out on the Kiwis' triumph last year.

Williams has only played 20 NRL games in the past two years because of his injury problems.

Bulldogs coach Steve Folkes said the club was surprised by Williams' latest injuries because the player had done relatively little impact training.

"It's unusual because he hasn't done a lot of running," said Folkes.

"We are already (managing him) so we're a bit puzzled as to why it happened.

"It's not a major thing, it's not the end of the world."