Kolo Toure will sit out Celtic's glamour friendly with Barcelona - but could be thrown into action in next week's crucial Champions League clash with Astana.
The former Arsenal, Manchester City and Liverpool centre-back has yet to feature for his new side since signing last week.
And with the 35-year-old Ivorian international still lacking match sharpness, Parkhead boss Brendan Rodgers has decided not to risk him against Barca stars Lionel Messi and Luis Suarez when they take on the Spanish giants in Dublin on Saturday.
However, Celtic coach John Kennedy says Rodgers has not ruled out handing Toure his Hoops debut when they welcome their Kazakh opponents to Glasgow for Wednesday's all-important second leg.
The Scottish champions - who claimed a valuable 1-1 draw in last week's opening third qualifying round tie - are worryingly short on defenders with Erik Sviatchenko, Jose Simunovic, Dedryck Boyata and Kristoffer Ajer all currently unavailable through injury.
Swede Mikael Lustig has also been left out of the travelling squad heading to Ireland, while Kieran Tierney did take his seat on the flight but may sit out the Aviva Stadium friendly after suffering cramp in last week's match.
Kennedy, speaking as the Hoops departed Glasgow Airport, said: "It's pretty much the same squad we had in Astana.
"Kolo is still working fitness-wise so he also stays back to do some extra work. It's still a bit early for him to play in tomorrow's game. We will look at that again and assess that on Monday.
"It depends how he comes through the next few days [whether he can face Astana next week]. If he shows his fitness levels are good enough he is an option.
"Erik won't travel over. We'll see how he is in the next couple of days. It's better for him to stay at home and get some treatment.
"Mikael Lustig hasn't travelled either. That's just a precaution.
"Right now we just have to go with what we've got. The majority of the squad are here and most will take part against Barcelona.
"We just have to deal with tomorrow and see how everybody comes through. We've got Kolo in the back of our minds and that is why he has stayed behind to work.
"Come Sunday we can assess everybody and see where we're at.
"We are short defensively, though. There's no question about that. We just have to make sure whatever we put on the pitch against Astana is strong enough to win the game."
On top of their defensive absentees, Stefan Johansen has also been given the weekend off after his wife gave birth on Friday morning, but there is at least some good news on the injury front, with Simunovic stepping up his recovery work after six months out with a knee injury.
"Jose was out on the pitch today and that is good to see," added Kennedy. "He's been out a long time but he needs time to get his levels back up to the point where he can rejoin the group. But the signs are positive."
But the Celtic players who do feature against Barca can expect a tough examination, Kennedy has conceded.
"We're playing a top team so it's good to test yourself against that," he said. "For us it is good preparation for Wednesday.
"Testing yourself against the best gives you a great mark of where you are at.
"Barca will probably make us run a little bit so that will help us top up our fitness levels as well."
Meanwhile, Kennedy has confirmed that Rodgers is interested in luring Scott Sinclair to Scotland.
Reports claims the Northern Irishman has so far failed with three bids for the Aston Villa winger.
The Birmingham outfit are demanding £5million for the player, who has previously worked with Rodgers at Swansea, but Celtic's latest offer came in at just £2.75m.
However, Kennedy admits the 27-year-old would fit the bill if a price could be agreed.
He said: "There are a number of targets we're looking at but we need to make sure they are the right ones.
"He [Sinclair] is one that has been mentioned but he's still an Aston Villa player. We want to bring quality in and that is certainly the calibre of player we're looking at."