Celtic manager Neil Lennon believes captain Scott Brown might only be fit for one of Scotland's two forthcoming World Cup qualifiers.
Brown was recalled to Craig Levein's squad after missing the opening two home qualifiers against Serbia and Macedonia with an ongoing hip problem.
"I have spoken to Craig and he knows what the situation is," said Lennon.
"He will go to Scotland and he will play, but I don't know if he will be able to play the two games."
Midfielder Brown had to take anti-inflammatories and an injection to take part in Celtic's 3-2 Champions League win over Spartak Moscow in Russia on Tuesday.
"Bownie will struggle for Sunday," said Lennon.
"He put in another remarkable performance on Tuesday, because he didn't train on the Monday.
"He did two strikes in the warm-up and walked off."
He is struggling to be ready for the visit of Hearts in the Scottish Premier League on Sunday but remains in national coach Levein's squad for the trips to Wales and Belgium.
Celtic winger Kris Commons had earlier this week said he was baffled why he was not in the Scotland squad.
"He's playing very well and started the season brilliantly," said Lennon of the former Derby County midfielder.
"He's been a big player for me and the club and I'm disappointed for him that he's not in the squad.
"There was a real desperation about him the other night to play.
"It was a difficult team to pick, but you could see the hunger in Chris and how much it meant to him.
"His fitness levels are fantastic now. He's worked on that aspect of his game, but we've always known he is a good player.
"But Craig's the manager. He's made that decision and explained his decision publicly.
"And Chris accepts that and will just keep playing away."