The Greece international joined the Cottagers for £11million from Olympiakos in deadline day but brought with him to London a knee injury which has kept him on the sidelines since his arrival.
"We're still working very hard to get him up to speed for the Premier League," manager Rene Meulensteen said.
"It's important for us that we time that right, for us and for him.
"He's working hard, he's progressing every day, and that's how we assess him. Wednesday will be too early for him."
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