Defender John Souttar is absent from Rangers' Scottish League Cup final squad.
The Light Blues centre-back was forced off in the first half of Thursday night's Europa League draw against Tottenham Hotspur, with manager Philippe Clement initially unsure the extent of the injury.
But speaking to BBC Scotland ahead of the Hampden Park clash on Sunday, Clement confirmed that the Scotland internationalist will be likely be sidelined for the entirety of a busy festive schedule.
He said: "No, John Souttar will be injured for several weeks. He's not in the squad."
Asked how he feels Leon Balogun, his replacement for the afternoon will cope, the Rangers boss replied: "He's an experienced guy and he's looking forward to the big games. So, he's up for this."
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Rangers go into the game in much better form than the first Old Firm clash of the season having drawn 1-1 with big-spending Spurs on Thursday and improved their attacking play domestically.
Asked what was different now, Clement said: "Simple things in football, eh? Making goals and not conceding. No, it's not that simple of course - to play a really big performance with the whole squad being good in all the details.
"It's about a lot of details, it's about a lot of energy, it's about a lot of work effort, it's about a lot of braveness also and doing the right things. The team is growing in that way the last couple of months, clear to see for everybody. It's now repeating this very shortly after the Tottenham game.
"Everybody comes to Rangers to win trophies. All the players, all the fans want that. It's a massive thing to do so we know the importance of this game and we're all looking forward to that and to grab this trophy again. We had the feeling last season so we want to have the feeling again.
"This is a game at Champions League level. But the approach, there's not such a big difference.We're on the right track, that's clear and there's still a lot of work to be done. This will be a massive one again to get experience out like the Tottenham game was.
"[The game plan is] to be good, compact, to be aggressive, to impose our style of playing also on the ball and to create the right spaces against Celtic, where we want to get the ball and to hurt them in that way. It's not only about starting XI, it's about all squad."
