Celtic assistant boss John Collins says the club are in danger of losing out on their January transfer targets if they do not clinch a place in the knockout stages of the Europa League.
Celtic claim a fee was agreed with Manchester City for John Guidetti prior to them taking the striker on loan.
Kris Commons is confident that Celtic will be at their best for the visit of Salzburg on Thursday night following the weekend's unconvincing 2-1 win over Dundee.
Celtic manager Ronny Deila was not pleased with his team's display in the 2-1 victory over Dundee.
Celtic held off spirited Dundee to take the points with a 2-1 victory with goals either side of the break proving decisive for the league leaders.
Celtic will be without captain Scott Brown when they entertain Dundee in the Scottish Premiership on Saturday afternoon.
Celtic chief executive Peter Lawwell reckons the Scottish champions have the potential to be among the biggest clubs in the world.
Celtic have announced captain Scott Brown has signed a new contract with the Scottish champions.