St Mirren are set to be without Australia international Ryan Strain for three months.
The wing-back is due to undergo surgery on the groin injury he suffered on international duty last month.
Manager Stephen Robinson said: “Ryan has gone to London for surgery. He will have surgery on Monday and unfortunately he will be in the region of three months, which is a huge blow for us.
“But it’s up to other people to step into the plate now. We have a small squad which is tested to the limit with injuries, especially long-term ones, but we are no different to anyone else.
“I don’t work on the excuse mentality, I try and work on the basis that someone else will get an opportunity to prove they should be in the side and make up for Ryan’s loss.”
The 26-year-old is approaching a crucial time in his career with his contract due to expire at the end of the season.
Robinson said: “We spoke with Ryan’s representatives about a new contract and they weren’t interested at that stage in terms of signing.
“Ryan has obviously had a huge blow with his injury and it’s a blow to us because Ryan has been a big, integral part of what we have done in our relative success.
“But you can’t feel sorry for yourself. Ryan will get the best medical treatment possible and he’s got the best physio around that will help him get back.
“He has to buy into that, he has to have the attitude and the work ethic that Jonah Ayunga had with a long-term injury.
“His aim as a young man is to come back stronger and fitter than he was before.
“Then the decision is in his hands in terms of what he does the following season but hopefully he will be back long before then.”
Saints take on Rangers at Ibrox on Sunday and Robinson is optimistic they will show more belief than they did in Tuesday’s 1-0 defeat against Ross County, who scored late on through Jordan White.
“You need belief,” Robinson said. “We have got the talent.
“Our lessons from Tuesday night, my biggest frustration wasn’t actually losing the game. If we had drawn the game I would still have been frustrated with our performance because we didn’t put our stamp on the game, our style on the game.
“That has to be what we do at Ibrox, we have a belief that, when we land on the ball, we can play.
“We believe we have players who can hurt Rangers in certain areas and we will go there with a belief.
“We learn our lessons, you have ups and downs. It’s never going to be smooth journey as a football manager or a football squad but we have a group of players who totally believe in each other.
“We looked like we didn’t have a little bit of belief for certain periods but we have spoken about it and I’m sure will be better for it.”
