The British Lions wing has not played since returning from New Zealand with a similar problem to the one that has ruled out team-mate Gavin Henson until mid-October. Now he is targeting a similar comeback date as he battles to prove his fitness for Wales's opening game of the Autumn Series, against the All Blacks in Cardiff on November 5.
Ospreys assistant coach Sean Holley said: "It is a worry because Shane just hasn't been able to shake off the problem but it is still our hope that he will be fit for the Heineken Cup and then for Wales in the Autumn."
Williams is the sixth member of Mike Ruddock's squad to be sidelined by a groin problem.
As the countdown continues for RWC2015, Tournament Chief Executive Debbie Jevans visited the Millennium Stadium to discuss preparations for the eight matches and reveal the positive news that 100,000 tickets for games at the home of Welsh rugby have sold in the last seven days.
Jason Harries is targeting a first win on the World Series circuit this season with Wales. The series returns to action this weekend in Dubai where Harries is part of a team hoping to build from its efforts in round one in October.
Wales skipper Jevon Groves says his side have addressed a few points from Gold Coast and aim to 'hit the ground running' in the next two rounds of the World Series, kicking off with this weekend in Dubai before heading off to South Africa next week.
Wales Sevens manager Steff Thomas is hopeful his side can build from a quarter-final spot in the opening round of the World Series in Australia when his side take part in the forthcoming double header in Dubai and South Africa.