Fielding has missed the Rams' last seven matches since suffering a groin injury in the Championship draw at Middlesbrough at the start of October.
The 24-year-old, playing as a permitted over-age player, completed the full 90 minutes against rivals Nottingham Forest at their Nigel Doughty Academy on Tuesday afternoon. However, he could not prevent Derby losing the game 2-1.
The Rams included former Forest players Nathan Tyson and Kieron Freeman in their starting line up and took the lead courtesy of a Michael Jacobs penalty.
But the hosts hit back with second-half goals from former Manchester United midfielder Jonathan Greening and ex-Ram Marcus Tudgay.