"Danny Williams has a small fracture on the bone in his foot. We have a specialist appointment tomorrow, where we will get some information about how long he's out," Wagner told British media on Thursday.
"At the moment, this is very open as it is a very small fracture. He is definitely out for tomorrow and anything else we will know after the weekend," he added.
Wagner said he would make late calls on striker Laurent Depoitre and winger Rajiv Van La Parra ahead of the game with both players carrying knocks.
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"Lolo Depoitre is further along than Rajiv, with whom there is some doubt at the moment. So we have some injury concerns at the moment but we will find some solutions for it," he said.
"Collin Quaner is out too. He will be ready during the next international break," Wagner added of the German forward.
Huddersfield are sixth in the standings on eight points from five games, while Burnley have an identical record but are a spot below them on goal difference.
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by John O'Brien)
