The 21-year old has struggled since the end of last term and the news has not gotten any better with Boro boss Gordon Strachan confirming he will be out at the start of the 2010/11 season.
“Rhys won't be back for the immediate future,” Strachan told the Middlesbrough Evening Gazette.
"He'll not be back for the beginning of the season, that's for sure.
"He'll stay in Australia. There's a specialist there who's not with the Australian FA, he's a specialist that our head physio Grant Downie knows and he'll stay there for a while."
Williams was dropped from Australia’s World Cup squad because of the injury and it brought about bad blood between Strachan and Socceroos coach Pim Verbeek who laid blame on the Teessiders for playing him when he was unfit.
But Strachan said that Williams’ injury was that bad he should never have gone to South Africa even to attempt to make the final 23.
"We knew Rhys had no chance of playing in the World Cup Finals,” he added.
"I told the Australian people that the lad would struggle but they said they were happy with what they'd seen and that they would make him better for the World Cup Finals.
"Being a young man, he wanted to try his best to get into the World Cup squad, which is understandable, and that's why he tried to get fit for the last couple of our games last season, to show he was fit for the World Cup.
"But he wasn't fit. I knew and he knew he could only do a certain amount."