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The 33-year-old lasted just 30 minutes of the All Blacks' 16-15 victory over England at Twickenham before he left the field and coach Steve Hansen said the Auckland Blues centre would not be back for next week's clash with Ireland in Dublin.
"He's got a grade one AC (separated) shoulder," Hansen told reporters. "He may be (out) for a week, maybe two."
The All Blacks face world number two Ireland next week, with their likely strongest possible side, before they end their November tests schedule against Italy in Rome on Nov. 24.
The imposing inside centre was unlikely to have played against the Azzurri anyway, as Hansen had intended to give his fringe players game time on their end-of-season tour as he fine-tunes his Rugby World Cup plans.
Hansen said it was too early to determine whether they would send for a replacement player, although Ngani Laumape looms as a likely call-up if needed after impressing with a hat-trick of tries against Japan in Tokyo last week.
"We haven't had time to discuss that," Hansen said of the possible need to add to his squad. "We will see how he pulls up in the morning, and have a bit of a chat about it later."
Even if Williams is fit to face Italy, Hansen may still opt to end his difficult year early and give him an extended off-season to prepare for the 2019 Super Rugby campaign.
Williams has had wrist, knee and shoulder problems, and played just five tests this year, lasting the full 80 minutes in just one of them.
He also played just six games for the Blues and was under scrutiny in rugby-mad New Zealand for underperforming when he did take to the field, although Hansen added that he was the type of player whose form improves with matches.
Hansen's midfield selections, however, should be a formality next week, with Ryan Crotty performing well against England when he replaced Williams and likely to partner Canterbury Crusaders team mate Jack Goodhue against the Six Nations champions.
Reporting by Greg Stutchbury; Editing by John O'Brien