Celtic boss Ronny Deila says keeping his best players will take priority over acquisitions in the transfer window.
Chelsea striker Fernando Torres is understood to be set for a return to Atletico Madrid, according to Sky sources.
Rotherham have signed Blackburn defender Jack O'Connell on a youth loan.
The England youth international, 18, who can play centre-back or left-back, will stay at New York until January 5 and could make his debut in Saturday's League Two clash at Exeter.
The news comes on the same day as Josh Morris returns to Rovers from Steve Evans' Millers after his loan spell was cut short following a knee injury.