Brendan Rodgers is leaving the door open to Ryan Christie and Scott Allan.
Both players spent last season out on loan and are in the final year of their Celtic contracts.
The transfer of Stuart Armstrong to Southampton has reduced the competition for midfield places but Rodgers is expected to spend to enter the transfer market.
Christie and Allan both have bags of ability but question marks remain about their strength and consistency to play at the level Rodgers demands.
Two years ago Armstrong was on the outside looking in as Rodgers started to reshape Ronny Deila’s side with the Irishman refusing to rule anyone out of his plans.
“The two boys have come back and my duty to them is to make sure they are at their highest level fitness wise,” he told The Sun about Christie and Allan
“Then we’ll see over the course of the pre-season. Both players have looked very good.
“When I look at Ryan’s situation, it was to get him out and get him stronger. The Aberdeen loan was perfect for him.
“It’s partly where these boys see themselves as well.
“I might want to keep them but if I can’t give them as many games as they want it’s difficult.
“But both boys have come back looking strong and looking fit and have done very well.
I never rule out any player. I use my eyes, at how they train, I look at their commitment.
“You mention a guy like Dedryck Boyata.
“You get players that initially were out of the team, but they get better and they improve.
Then all of a sudden they are in the team and they are performing very well.
“So I don’t rule out any player, especially when you’ve got good players.”
Celtic return to Glasgow from Austria tomorrow after a double header against Sparta Prague and Blau Weiss Linz.