The 28-year-old, a free agent after being released by Midlands rivals Leicester this summer, caught the eye as he played just over an hour of the Rams' opening pre-season fixture at Burton 10 days ago.
However, after training with the Rams last week the Australia international was left out of the squad that played Chesterfield in the Derbyshire FA Centenary Cup on Saturday prompting some to
suggest that any deal may be dead.
But manager Nigel Clough said: "It's nothing like that. Patrick just felt that there wasn't much point in him playing another game and risking injury if there wasn't a deal agreed.
"It is something we are discussing with him and his representative at the moment and it is ongoing."