The former Maribor defender, 31, has agreed to an initial short-term contract until January after impressing Robins in a recent week-long trial, but he has yet to finalise the deal.
Robins said: "Suad Filekovic is back in the country and we will look to get things sorted. He has experience, stature and is ready for the Championship. It is a win-win situation for all of us and it was a real no brainer."
Andy Gray and on-loan Hull defender Nathan Doyle are cup-tied, but another recent signing, Julian Gray, should continue in midfield after making his debut on Saturday in the goalless draw with Swansea.
Emil Hallfredsson is struggling with a knee injury, Daniel Bogdanovic is recovering from an ankle problem and Jamal Campbell-Ryce (eye) is not yet ready to return after being hit in the face by the ball in the recent defeat at Watford.
Iain Hume is expected to be included after having stitches inserted in a cut eye after Saturday's clash.