Swansea, who are up to ninth in the Championship thanks to their 2-1 victory over Plymouth, are back in action against Sunderland this Saturday.
They go to Hull City in their final pre-Christmas game, on 21 December, before festive home fixtures against Queens Park Rangers and Luton Town.
Williams’ side then travel to Portsmouth on New Year’s Day, before West Bromwich Albion come to the Swansea.com Stadium on 4 January.
Allen has been a regular in Williams’ matchday squads this season, making 15 club appearances so far, while he has come out of international retirement to be part of Craig Bellamy’s Wales squad.
“Joe will do everything, he is an incredible pro, and the medical team will help him,” Williams added.
“Hopefully we’ll be able to see him at the back end of the Christmas period.”
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