A match that looked destined to finish scoreless has seen Copenhagen take a late lead on Russian champions Rubin Kazan, 1-0 in Denmark.
Dame N’Doye has headed the hosts in front just minutes before full-time, putting the Danes on course for a mild surprise on the first day of group play.
Copenhagen and Rubin are in group D with Barcelona and Panathinaikos, with Barça leading the Greek champions 3-1 at Camp Nou.