For Mohun Bagan, who is on the top of the table, it was the first time they were defeated in the present Hero I-League tournament.
Joel Sunday of the home team scored the first goal at the beginning of the match, while Mohun Bagan's Glen scored the equalizer in the 24th minute after which Chhawnkima of AFC shot the winning ball in a penalty.
AFC Captain David Rinmuana was awarded 'Hero of the Match' for the fourth time today.
With this AFC has played 12 matches and bagged 12 points to hold seventh position in the table.