In each group, teams play against each other home-and-away in a round-robin format. The group winners and runners-up advance to the round of 32, where they are joined by the eight third-placed teams of the 2018–19 UEFA Champions League group stage. The matchdays are 20 September, 4 October, 25 October, 8 November, 29 November, and 13 December 2018.