Celtic midfielder Beram Kayal has been ruled out of action for at least a month with an ankle injury.
The Israel international was carried off on a stretcher following a challenge with Lee McCulloch during the 1-0 win over Rangers.
"Beram Kayal has undergone two sets of scans on the ankle injury sustained on Wednesday evening," Celtic have said.
"And results received today have revealed that unfortunately he will be out of action for at least one month."
More will be known following further tests on the injury, suffered as Celtic overtook their city rivals to go top of the Scottish Premier League.
"The midfielder, who missed the closing stages of the win against Rangers in midweek, will receive a further investigation on the injury in one week," said the statement on Celtic's website.