With three trailists sent away and another, Estonian Andrei Stepanov, cut down by a hamstring injury, there is still a lack of bodies covering the defensive front.
However, Tilly refuses to make any panic signings just for the sake of calming supporter nerves.
'Come to the Blues for nothing lads, you know it makes sense'
The Blues boss is hoping as the new season gets closer players, and their agents, will be running out of options to sign on the dotted line.
Tilly told the official site: "There is no point in just bringing someone in for the sake of it. We do need a new centre back but we've spoken to one who we are still waiting to hear back from and there a few others available too so we're certainly not worrying about the situation. We want to make sure we get the right person in and that can take time. We have a couple of left-backs we are interested in. But that's all I can say on the matter right now."