Motherwell aim to go back into the transfer market after losing Northern Ireland international Liam Donnelly for about two months.
However, manager Stephen Robinson admits finding a fit full-back could be like searching for a needle in a haystack.
Donnelly has played at the base of Motherwell's midfield over the past 12 months but his experience in the back line had been set to be utilised after they lost three left-sided defenders to injury.
The 22-year-old, who has two caps, is set to miss Northern Ireland's Nations League openers against Romania and Norway next month and the Euro 2020 play-off semi-final against Bosnia and Herzegovina on October 8.
Manager Stephen Robinson said: "We have been told he could be out a minimum of two months. It's a knee problem, he will go to the specialist and get a proper diagnosis.
"We're not sure if he needs surgery but it will be a minimum of eight weeks, probably a little bit longer."
Donnelly had been earmarked for a run at left-back after Nathan McGinley was ruled out with a groin injury to join long-term absentees Charles Dunne and Jake Carroll on the sidelines.
Ricki Lamie moved there from his central role with Bevis Mugabe slotting in at centre-back as Well lost 1-0 to Dundee United on Saturday.
Robinson, whose team are looking for their first Scottish Premiership point of the season when they host Livingston on Wednesday, said: "The curse of the left-back position – he only played there 20 minutes in training.
"That gives me a problem, we have got injury problems at the back. Ricki played well there and it was Bevis's first competitive game in a long, long time.
"We are actively looking to try and get someone in in that defensive position. What's available at this time of the season is virtually nothing because England aren't playing, people haven't played since March in the lower leagues.
"I need someone to come in and hit the ground running with a minimal amount of money to spend. That reduces it down to a needle in a haystack. But we will keep searching.
"Charles will be longer, we are hoping Jake will be back start of October/middle of October. Nathan McGinley will be back after the international break.
"So it's a short-term problem that if everyone stays fit then we can cope with. If we get another injury then it will be something that could cause me a problem.
"We haven't got any of the younger boys ready to go in those positions but we can shuffle things about.
"Liam Donnelly was our versatile one, so losing him is a big blow."