ISL club ATK Mohun Bagan are clubbed with Bangladesh's Basundhara Kings, Maldives' Maziya S&RC and the winner of the play-off round in the Group D (South Zone) of the AFC Cup 2021. The winners of the preliminary round two will square off in a play-off clash and the winner of that match will join the other three clubs in Group D. ATK Mohun Bagan, after their merger, took Mohun Bagan's AFC Cup group stage slot which they had earned by winning the I-League last season. As a result, the qualifying preliminary (round two) slot which was reserved for the ISL champions ATK, went to Bengaluru FC as they finished third in the ISL 2019-20 league campaign.