The Championship side recently released Shane Lowry, which leaves the club needing to bolster their ranks before the deadline.
Gary Rowett has admitted that Birmingham City's acquisition of Diego Fabbrini will probably be their last permanent signing of this window, but suggested that the Italian may not be the last new face through the door at St Andrew's before the deadline, the Birmingham Mail reports.
As well as Fabbrini, this month the Championship side have signed youngster Luke Maxwell, brought Will Buckley in on loan and have extended James Vaughan's loan until the end of the season. And with the four deals bolstering the club's attacking options, Rowett is hoping that the remaining days of the window can be used to add some defensive depth.
"I think Fabbrini is the last permanent one we'll see in this window which is why we've done it," he told the Mail.
"I think now it's a case of trying to find a loan option that maybe at the end of it could become our player.
"I think we've still got room for one full-back/centre-back/ defender who can play in a couple of positions and that would give us some fantastic flexibility."
So far this season, the lack of options in that area of the field has had little impact on their fortunes on the pitch. They currently sit seventh in the Championship, level on points with Sheffield Wednesday, who occupy that final top six spot.
But the side's need for a new defender has become greater in recent days with the Mail reporting that Shane Lowry has left the club.
And as the season continues with games coming thick and fast, Rowett is clearly aware that not addressing the issue before Monday's deadline may severely damage the club's hopes of remaining in the promotion mix.