The Official Online RBS 6 Nations Store is open. The store has everything you need to get behind your team during the RBS 6 Nations, plus the store is now fully stocked with a much wider range of rugby merchandise.
Williams had treatment on Tuesday to help settle the problem in the "short term" and is out for two weeks.
He could be back for either the Munster or Perpignan games early January if he responds well to treatment, the Ospreys confirmed.
"The problem is affecting one of the rotator cuff tendons in his right shoulder," it said in an Ospreys statement.
"After being reviewed by a shoulder specialist, Shane has had treatment to try and help his symptoms in the short term.
"Unfortunately this rules him out of action for the next two weeks."
Williams - Wales's leading try scorer with 44 touchdowns from 61 caps - was a Lions Test player in 2005 and will be desperate to tour again in 2009.
In a golden 2008, the Glanaman man helped Wales to the Grand Slam, won the RBS Six Nations Player of the Year award, and was voted BBC Wales Sports Personality of the Year.