Rangers have been rocked by the news that Jeremy Clement's injury is worse than initially feared.
The French midfielder damaged his knee in Saturday's 2-1 defeat to Hibernian, and was immediately ruled out of Gers' next two matches.
Paul Le Guen had been hoping to have Clement back in time for next week's Uefa Cup clash against Molde, but a scan has confirmed that he will be out for longer.
The 22-year-old will now remain sidelined for about a month, and Le Guen admits that it is a major setback, especially ahead of Saturday's key game against Celtic.
"It's a big blow because he was very important to us at the beginning of the season," Le Guen commented.
"In such a game like the Old Firm it is important to have all your main players.
"I hope he will be out for less than a month but it's a bad injury and he will be unavailable until at least after the next international break."