Neil Lennon has been quizzed over Celtic's transfer interest in Ben Davies and Alfie Doughty.
The Parkhead boss insists he won't drawn on individual players but confirmed the club are in the market for a left-sided defender.
Boli Bolingoli 's loan move to Basaksehir leaves Lennon with only Greg Taylor left at his disposal.
It's understood Preston defender Davies is under surveillance while two bids for Charlton midfielder Doughty, who can also play at left-back, have been rejected.
On Boli's departure, Lennon said: "It means there is a vacancy there now that needs to be filled.
"So yeah, we are looking in that position."
The Addicks have told Celtic they don't want to sell Doughty, despite his contract being up in summer 2021.
Boss Lee Bowyer has urged the youngster to sign a new deal to remain in London for regular first-team football.
Lennon, meanwhile, kept his cards close to his chest on both Davies and Doughty ahead of Wednesday night's Premiership clash with St Mirren.
He added: "It is just speculation at the minute, if it is the right fit for the club and the team and the squad and it is within the financial budget then we will look to do that.
"In terms of names I can't give you any at the minute."
