Celtic captain Stephen McManus has been ruled out of Saturday's Old Firm derby through injury.
McManus has been playing through the pain barrier in recent weeks with an ankle problem and he sustained a knee injury during last weekend's win over Aberdeen.
The Scotland international has failed to shake off the latter problem and he will now miss the title showdown at Ibrox.
The news is a blow for Celtic boss Gordon Strachan as they look to cement their position at the top of the table.
Glenn Loovens is expected to replace McManus in defence alongside Gary Caldwell.