Glentoran head coach Mick McDermott admits it will be a case of wait-and-see over Hrvoje Plum's knee injury.
Plum appeared in pain and required assistance after picking up the knock during Saturday night's 2-1 defeat to Larne at Inver Park.
The Croatian midfielder has been one of the Glens' star players this season, scoring 12 goals for the East Belfast club who sit top of the Danske Bank Premiership.
There are concerns that Plum may have sustained cruciate ligament damage, but McDermott says the extent of the injury won't be known for another day or two.
"Hrvoje hyper-extended his knee and jarred it. There is likely some damage there, but we don't know the extent of it," he said.
"It will probably be Friday before we discover how serious it is, when the swelling goes down."
McDermott added: "I don't think Hrvoje has done his ACL. He did his other one and he said this feels different.
"But he did feel something at the time when his leg hyper-extended, so hopefully it is just a sprain.
"But we don't know, and won't know until Friday."
Meanwhile, McDermott revealed he visited Larne striker Johnny McMurray after Saturday's game.
McMurray was stretchered off after colliding with Glentoran goalkeeper Marijan Antolovic as he bundled home the winner.
And a subsequent scan has revealed the 25-year-old, who has scored 11 goals since joining the East Antrim club from Ballymena United in the summer, has damaged his cruciate.
"I went in to see Johnny McMurray after the Larne game, and I just said to him that I hoped he would be okay," McDermott said.
"You don't want to see any player pick up a serious injury. It looks a bad one for Johnny which is a shame."
