Celtic striker Jan Vennegoor of Hesselink is expected to be sidelined for up to a month - ruling him out of the Champions League double-header against Manchester United.
The Dutchman has not played since sustaining a groin injury in the opening seconds of the Clydesdale Bank Premier League win over Hamilton on October 4.
He will sit out several important SPL matches - including tomorrow's trip to Inverness - but his absence from the European stage is arguably an even bigger blow for the Scottish champions.
As well as Tuesday's clash at Old Trafford, he is also likely to miss the return match at Celtic Park on November 5.
Boss Gordon Strachan confirmed the big forward is expected to be out for "three or four weeks", adding: "He will not be ready for a while yet."
Strachan is also awaiting the return of Georgios Samaras, Shunsuke Nakamura, Scott McDonald and Artur Boruc before assessing their fitness after the international break, but does not anticipate any problems.
Those who turned out for Scotland at Hampden last Saturday have all reported back for training this week, with Scott Brown in particular earning plaudits for his performance in the goalless draw against Norway.
He was deployed in the holding role shielding the back four against the Scandinavians and also played an important part in driving the team forward in the second half, prompting Strachan to declare Brown can now play anywhere in midfield.
But the Hoops boss still favours the attacking aspects of the player's game, as opposed to his defensive qualities.
"Scott is now in a state of mind where he can play in any midfield position," said Strachan.
For a while, he played in a role that he'd done through all his years. But then he had to change it to a different style of football.
"He now knows where he should be in conjunction with the ball. That's good for him because, if he knows where the ball is going to be, it makes the game easier.
"Scott will play different roles for us because he can. I wouldn't say he's better as a defensive player because you cannot take away what he's got.
"He's now got a lot more his locker. Scott has football ability and the fitness which allows him to move into different positions.
"Some people can't play four or five different positions because their ability doesn't allow them to do that."
Inverness boss Craig Brewster believes Celtic's stars will be playing for their places in the Champions League clash with United when they visit the Caledonian Stadium.
He said: "They don't get bigger than those sort of games and I'm sure all the Celtic players will be desperate to play their way into contention for that one. That is why we will have to be on top form on Saturday."
Meanwhile, Brewster is keen to keep trialist Ibrahim Atiku at the Caledonian Stadium for a bit longer before deciding whether to offer the Ghanian a contract.
The speedy winger has attracted the attention of Manchester United and Borussia Dortmund in the past and has been playing for Swedish side IF Sylvia most recently.
Brewster said: "He has trained with us all week and we are seeing if he can get clearance for next week's reserve match."