The Wales and Lions wing tore a hamstring in his country's defeat to Australia in late November and hasn't played since.
It had been feared that the 32-year-old would not be fit in time for the Six Nations but his recovery process is progressing even better than expected.
"Shane is less than two weeks away from returning," said Ospreys director of rugby Scott Johnson.
Williams will miss the Boxing Day clash with the Scarlets and the New Year's Day encounter with the Blues but he could now feature against Ulster in the Magners League at Ravenill on January 8.
Williams, who has played Celtic League rugby with the Ospreys since their formation in 2003, is just one game shy of 60 Magners League appearances.
He currently has 57 starts and two substitute appearances to his name and has scored 24 tries and 123 points in that time.
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