The Blues centre-half is a summer target for a number of Premier League clubs after slipping out of the top flight last season.
Stoke are among those leading the chase and hope to steal a march on their rivals by making an early move.
It is understood that a bid has been lodged, with some papers suggesting it is £12million, and talks between the two clubs have begun.
The Potters can, however, expect to face stiff competition for Dann, with the race for his signature set to hot up.
Aston Villa are preparing to make an approach, with new boss Alex McLeish having worked with the highly-rated 24-year-old at St Andrew's.
Long-term suitors Arsenal and Liverpool are also believed to be readying moves, with Arsene Wenger and Kenny Dalglish in the market for defensive reinforcements.