On 24 August 2009, it was announced that Harnik was able to leave his club SV Werder Bremen as a free agent, and six days later was loaned out to Fortuna Düsseldorf.
Pe 24 august 2009, a fost anunțat că Harnik va putea să părăsească clubul SV Werder Bremen drept jucător liber de contract, însă șase zile mai târziu a fost împrumutat la Fortuna Düsseldorf.