Rangers are sweating over the fitness of Dado Prso ahead of this weekend's first Old Firm clash of the season.
The striker is struggling with a knee injury which forced him to miss last weekend's defeat at Hibernian.
Gers boss Paul Le Guen is not sure if the Croatian hit-man will recover in time for the trip to Celtic.
"I don't know yet. He is important for the team and he has played many important games this season," said Le Guen.
"But he was injured and couldn't play against Hibs. I regret that, but I had no choice."
Le Guen is looking forward to his first taste of the Old Firm derby and has called on his players to rise to the challenge.
"It's a big task, but it's a great task," added Le Guen.
"It was a tough game against Hibs and we need to do better to get better results, that's clear.
"Too many players were too far from their normal level and, when that's the case, it's difficult to get a good result.
"It's frustrating, but we must not give up. We must believe that we will solve the problem."