"Georgios has a bit of time to think about his future," he said after Celtic's 4-0 win at St Mirren on Sunday.
"He won't be coming to Turkey (for the midseason camp), he will be staying to have some treatment and hopefully we will have an answer one way or the other on his future when we come back.
"He had a meeting with (chief executive) Peter (Lawwell) yesterday. You are never confident one way or the other. He has a lot to think about.
"It is a big contract for him, he is 29 so the next three or four years of his career is important.
"We would like him to be here but that may not be the case."
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