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.
The 20-year-old former Wigan trainee is yet to make a first-team appearance for the Latics but he is currently first choice at Northampton in League Two, where he is on loan.
Wigan boss Roberto Martinez told www.wiganlatics.co.uk: "Seeing Lee's progress from a young age has been a joy and to have him stay here and continue his hard work is great news.
"Lee is a great goalkeeper and he has shown that at Northampton this season. He has had some outstanding performances and we are really looking forward to continuing to work with him."