 Mumlek made just nine appearances for Dinamo in the Croatian First League and went on to return to Varteks in January 2000, staying with the club until August 2003, when he moved to Belgian side Standard Liège, which was the only time during his career that he had played his club football outside Croatia.After spending two seasons with the Belgian side, he returned to Croatia in July 2005 and signed with Slaven Belupo.In June 2007, he returned to Varteks for his third spell with the club.