Celtic striker Mohamed Bangura could be out of action for up to three months after picking up a knee injury.
The 22-year-old, who was bought from Swedish outfit AIK for £2.2m in the summer, will see a specialist on Wednesday and could require surgery.
Bangura has made only two starts since arriving in Glasgow, the first being in the 1-1 Europa League draw with Udinese in September.
And he was injured after coming on as a substitute against Rennes last week.
That was the Sierra Leone international's seventh appearance as a replacement and he has yet to score for his new club.
Celtic manager Neil Lennon said: "Bangura is going to see a specialist tomorrow and, after that, we will know whether or not he requires surgery on his knee problem."
Lennon has already lost Kelvin Wilson, Emilio Izaguirre and Scott Brown to long-term injury and the manager revealed that Mark Wilson is playing through the pain of a knee injury that is likely to eventually require surgery.
Meanwhile, fellow defender Glenn Loovens has joined striker Georgios Samaras and winger Kris Commons, although now clear of suspension, in missing Wednesday's Scottish Communities League Cup quarter-final against Hibernian through injury.
"We are hoping Glenn Loovens will be a week to 10 days from Sunday," said Lennon.
"Charlie Mulgrew is pretty doubtful as well with an ankle problem.
"Georgios Samaras is still struggling with bone bruising on his ankle and Kris Commons has a calf strain."
Lennon was not, however, for making the injuries an excuse for falling 10 points behind Scottish Premier League leaders Rangers, with whom they played a closed-doors friendly for fringe players on Monday.
"Thomas Rogne played an hour yesterday in a bounce game against Rangers and is definitely in contention and Victor Wanyama can play at the back," said the Celtic boss of his defensive options for the trip to Edinburgh.
"Daniel Majstorovic is fit and Mark Wilson has played centre-back before, so we have decent cover at the back."
Striker Gary Hooper was also confident that Celtic had sufficient strength in depth to cope.
"There are a lot of injuries all over the squad, but we've got the players to deal with it and on Saturday I thought we dealt with it very well," he said of the 2-1 over Aberdeen.