The Rams are in the market for a new shot-stopper following the exit of Marshall, who has joined Queens Park Rangers on free transfer.
First choice Ryan Allsop and his deputy Kelle Roos are the senior players available to Rooney between the sticks and he wants to have more options in that position.
The Derby boss has zeroed in on Stoke star Fielding as his top choice to replace Marshall this month.
Fielding only signed for Stoke in early December as a free agent and is yet to play for them, but could be on the move again soon.
The 33-year-old previously had several loan spells at Pride Park before permanently moving to Derby in the summer of 2011, remaining there for two more seasons.
Rooney is now keen on bringing Fielding back to Derbyshire with the player set to become a free agent shortly.
Derby are in administration and are only allowed to sign free agents or look for loan deals with no fee involved and Fielding is also tipped to be within pay limits allowed.
