John Hartson believes that David Turnbull could be on his way out of Celtic during the January transfer window.

The former Motherwell man has been in and out of the Hoops starting XI since he made his switch to Parkhead, but he has featured more prominently recently under Brendan Rodgers.

Turnbull has also fallen out of favour on the international scene in recent camps and a seat on the plane to Germany with Steve Clarke's side currently looks unlikely.

With this in mind, it has been reported that Turnbull will be allowed to speak to other clubs in January, with his contract set to expire in the summer.

Celtic will be keen to sell Turnbull while they can to ensure they make a profit on the attacking midfielder and Hoops hero Hartson reckons he will be on the move come the turn of the year,

He told Go Radio: "Sometimes the writing can be on the wall. I like David Turnbull. He's one of those players who can come back with double figures and are worth their weight in gold.

"Whether or not Brendan has got different ideas in terms of bringing in another midfielder or the other players he's got at the football club, with Reo Hatate still to come back, who knows? I like the lad but it looks like the writing is on the wall.

"I don't think Celtic have offered him a new contract, or maybe they have and he's turned it down. I don't know. He's in and out isn't he? He's not one of your McGregors or O'Rileys. He's out for a week and then comes back in and gets taken off. So my immediate thoughts are he's one of the players they would look to sell in January."