Alex McLeish has invited Celtic's Bobo Balde to train with Birmingham City while the Blues manager is also considering a number of other transfer options.
McLeish has confirmed the recruitment of defenders is his priority as he plots for the club's return to the Premier League.
Centre-back Balde is out of contract at Celtic Park in the summer and McLeish is keen to have a closer look at the 33-year-old.
"We extended an invite to Balde to train with us and that's as far as it has gone," said the Scot.
"We don't know if that will happen, there is a lot of water to go under the bridge. He has got internationals in the summer and I'm pursuing legitimate targets.
"Balde looks like he will be a free agent and I have to look at any opportunity I can get."
McLeish also refused to rule out a fresh approach for Rangers striker Kris Boyd, who was the subject of interest from Birmingham in the winter transfer window.
He said: "I'll look at every situation if I think a player can bring us some quality, but right now my priority is centre-backs.
"The budget is not limitless, I still have to be prudent.
"If there is money around after I get the priorities, then you never know. Boyd has certainly been on the radar for a long time but that deal is not imminent."
On Gers defender Madjid Bougherra, McLeish added: "He has done well but I would expect Rangers to ask for a high fee. It would maybe be too much for what we can afford."
However, Barry Ferguson could be a target for McLeish after the Blues boss expressed his continuing admiration for his former Rangers skipper.
"I know he has had injuries in recent years but, if he puts his mind to it, Barry can be anything he wants to be," McLeish said.
"I feel for him, the way it has happened. He came back from England and helped myself and my staff and the Rangers followers to a title in 2005.
"He came back in January as a really mature player, bringing the experience of playing in England. He was key to us securing that title.
"I think some people think he didn't do well in England. He had a slow start but after he came back from his injury at Blackburn he was one of the outstanding players in the league. A lot of managers told me that at the time."