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.
Sporting have removed Ricardo Sa Pinto as their coach after just eight months in charge, replacing him with Oceano.
The decision comes in the wake of the the Sportinguistas' 3-0 Europa League defeat to Videoton on Thursday, and a disappointing start to the season which has seen them fall five points behind leaders Benfica in a campaign that is just five games old.
The 39-year-old, who had two spells with Sporting as a player, has been offered a yet-to-be-accepted new role.
In a statement on their official website, Sporting said: "Sporting Clube de Portugal - Futebol, SAD's Board of Administration has announced that Ricardo Sa Pinto is no longer the club's first team coach.
"Sporting Clube de Portugal - Futebol, SAD thanks Ricardo Sa Pinto for his professionalism as a fan, employee and shareholder and would like to highlight the dedication that he has shown as Sporting's first-team coach.
"In light of his dedication to Sporting Clube de Portugal, the board of administration has invited Ricardo Sa Pinto to continue with the club in a role that will be announced should it be accepted."
Fifty-four-cap former Portugal international Oceano, who made over 300 appearances for Sporting, steps up from coaching the club's B team.