 As a member of the Croatian biathlon team, Fak won bronze medals at the 2009 World Championships and at the 2010 Winter Olympics where he was also the Croatian flag bearer at the opening ceremony.In 2010, Fak switched his citizenship and started competing for Slovenia.With the Slovenian team, Fak won four medals at the World Championships, including two gold, and a silver medal at the 2018 Winter Olympics.