Fabio Cardoso could quit Ibrox in January for a return to Portugual.
Cardoso signed for Rangers in the summer but hasn’t had much a look-in following Pedro Caixinha’s sacking.
Bruno Alves and Danny Wilson have been the first-choice pairing under caretaker boss Graeme Murty with youngster Ross Crorie first reserve.
Cardoso is wanted by Estoril and could be sold if Rangers can claw back enough of the £1.3m outlay they spent signing him for Vitoria Setubal in the summer.
KILMARNOCK want Aaron Tshibola on loan from Aston Villa.
Killie boss Steve Clarke is keen on a deal for the £5m midfielder, who is not in Steve Bruce’s plans.
Villa are keen to get him out of the club to play regular football and move to Rugby Park in January is now on the cards for 22-year-old.