Celtic legend Stilian Petrov insists the club must sort out the future of Kieran Tierney.
Arsenal have had two offers rejected for the Scotland international, who reportedly wants to join the Premier League club.
And Petrov has warned the Bhoys they must avoid a protracted transfer saga as they look to claim a ninth consecutive Scottish Premiership title.
He told the Sunday Post: "There comes a point in the careers of footballers that they weigh things up and make important decisions.
"Kieran Tierney may be in that position in this transfer window.
"If he goes, then the club will get excellent money for him. If he stays, then they are holding on to a quality footballer.
"But these are the kind of matters that you want resolved as soon as possible. It's important to know where you stand and what needs to be done."