Kieran Tierney is struggling to stay focused at Celtic amid interest from Arsenal, according to manager Neil Lennon.
Celtic have rejected two bids from Arsenal for the left-back, who has been a key figure for the Hoops in recent seasons.
Arsenal's second offer is reported to have been in the region of £25million, and although Lennon stated talks are yet to resume, he expects the saga to continue towards the end of the transfer window.
Tierney is not thought to have asked to leave the club, but Lennon acknowledged it is difficult for the 22-year-old to remain focused with his future up in the air.
"It is as we were a week ago," Lennon, speaking as he officially opened the Celtic Festival at Glasgow's Scottish Event Campus, said. "Two bids have been in, two bids have been rejected and that's where we are.
"How confident am I he'll still be a Celtic player come the end of the window? Well, you can never say never.
"That's going to rumble on. If there is interest in him then other clubs may come in or Arsenal may come again. I can't predict that.
"At the minute, he's working away in the background and it's difficult for him to keep focused because he's only human, but we're supporting him all we can."
Celtic have already signed a left-back this close season, bringing in Boli Bolingoli-Mbombo from Rapid Vienna, though Lennon suggested the Scottish champions have a further contingency plan in place should Tierney depart.
"We obviously have worked out other options if that worst-case scenario were to happen," Lennon added.