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.
Juventus goalkeeper Gianluigi Buffon is close to agreeing a short-term contract extension with the Serie A champions.
Buffon recently registered his 100th appearance in European competition as Juve qualified for the last 16 of the Champions League, but revealed he is not seeking a long contract.
The 34-year-old told juventus.com: "We need to speak about its length.
"I want it to be a short-term deal because I don't need reassurance; on the contrary, I think it's better to have motivation. In any case we're down to the final details."