Ross County full-backs Tom Grivosti and Connor Randall have both been ruled out for the season.
English defender Grivosti was struck down by a hamstring injury in November seven games into a comeback following a year out with a foot problem.
"Tom had an operation on his hamstring, so he will be out for the rest of the season," manager John Hughes said.
"When you talk football to Grivo, he talks football back to you. He understands the games and the tactics, but I have never had him since I came here. But he is a lovely lad and a big miss.
"Connor Randall has got a back problem and he will be out for the rest of the season.
"Connor got himself in the team and that back problem that he had previously raised its head again."
Other than the suspended Iain Vigurs, Hughes will otherwise have a full squad for Sunday's visit of Celtic and he is mulling over his options following their last game, a 2-0 home defeat by Dundee United.
County's home game against Hibernian was postponed on Saturday but Hughes has since been able to get back on their full-size training pitch.
"We actually came in on the Saturday and trained and we were out in the snow getting a bit of fun and fresh air," he said.
"Especially in the times we are living in, it's important that we stick together and they have something to do. So bringing them in sometimes helps them and their mindset. We had a great day, a good bit of spirit and fun.
"But it's only Monday that the snow cleared and we have been out on the big pitch, and that's made a big difference. You are getting your distances.
"We have had a few practice matches and you are playing for first-team places.
"I want to create that competition and that environment where, if they train really well, they get their place back in the first team. That puts you in a good place in terms of mindset.
"They are really competitive on the training pitch and I enjoy that. Some of them have given me a real headache in terms of selection."
