a total of 29 national associations were represented in the group stage. arsenal, atalanta, fastav zlín, 1899 hoffenheim, i̇stanbul başakşehir, 1. fc köln, lugano, milan, östersund, real sociedad, red star belgrade, vardar and vitesse made their debut appearances in the uefa europa league group stage (although milan and red star belgrade had appeared in the uefa cup group stage). vardar were the first team from macedonia to play in either the champions league or europa league group stage.