Chris Coleman is keen to bolster his defensive options following the departure of Daniel Fox.
The left-back completed a move to Celtic earlier this month and Coleman accepts he is now short of options.
Teenager Jordan Clarke impressed in the goalless draw at Huddersfield on Saturday but remains inexperienced.
Marcus Hall is the only established player able to fill the position and Coleman realises he will need to venture into the transfer market.
He told the Coventry Evening Telegraph: "We have only got Marcus Hall so we need someone else in that position because it is dangerous going with just one. You can't pin your hopes on one.
"Jordan Clarke played well again on Saturday and I can't tell you how pleased I am with him.
"He's been tremendous but it is not fair on him to pin our hopes on a 17-year-old with no experience, although I think he is going to be good.
"So we need to be looking for someone because we can't just rely on Marcus to play 46 games in what is a long and hard season."