The London club have made the right back position a priority after putting Paulo Ferreira up for sale and releasing Jose Bosingwa this summer. Newly-appointed boss Roberto Di Matteo has targets for this slot including Ajax's Gregory van der Wiel and Rafael da Silva but the Dortmund defender tops the list.
The full-back was watched many times last for Dortmund, and Chelsea scouts were impressed with his performances and his form at Euro 2012 with Poland recently. A move appears likely but the clubs are very far away from a similar valuation of the player. Dortmund are looking for around £15million whereas Chelsea want to pay £6million.
The deal looks set to ride on whether Chelsea will stump up a bit more cash, reports in Germany have also suggested Romelu Lukaku could move the other way on loan, making way for Piszczek and £8million to be exchanged.