The recent signing, who had impressed in his initial outings as a Spireite this summer, rolled his ankle towards the end of the game against Benfica B in Vila Real de Santo Antonio.
Boss Gary Caldwell revealed the extent of the bad news: “It’s worse than we thought, he might need surgery on his ankle.
“We didn’t think it was serious and the swelling the next day made Michael (McBride, physio) start to say this might be something worse than we thought.
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“His thoughts have been confirmed today.
“We have to deal with it and move on.”
Caldwell will wait for the specialist’s opinion but fears the former Peterborough man will be out for months rather than weeks.
It’s a bitter blow for Town, given that the man Binnom-Williams replaced, Dan Jones, missed a huge number of games over the past two seasons after ankle surgery.
The other injury victim from the pre-season tour, Joe Rowley, has seen a specialist already and will undergo an operation on his broken collarbone in the next 48 hours.
But his absence may only last around eight weeks.