Defender Darren Dennehy could join Barnet from under the noses of Bees boss Mark Stimson's former club Gillingham.
The defender, who recently negotiated a release from Cardiff, had been in discussions with Gillingham, where he spent a successful loan spell under the guidance of Stimson last season.
Current Gillingham boss Andy Hessenthaler believed his side had "done the deal".
But the Bees have since confirmed Stimson has been in talks with the 21-year-old over a potential move to Underhill.
The former Everton trainee moved to Cardiff from Goodison before loan spells with Hereford and the Gills.