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.
Wigan's Mauro Boselli is heading to Palermo after a loan move with the Serie A side was finalised.
Manager Roberto Martinez revealed the news after the striker was not included in the squad for the Latics 1-0 victory at Macclesfield in the FA Cup.
He said: "We agreed a loan period with Palermo and Mauro will go back to Italy where he had a spell with Genoa until the end of the season.
"That was the reason why he wasn't in the squad."