The 21-year-old is a free agent after leaving Sydney FC at the end of the A-League season.

Zadkovich can play in midfield or at right-back and is currently training with the Rams as he tries to earn a contract at Pride Park.

He recently had a trial with Crystal Palace and spent two seasons in England as a teenager, firstly with QPR and then at Notts County.

The Australia Under-23 international found the net once in nine appearances for Notts in the 2004-05 season before returning to his homeland.