Mumbai City FC finished the 2019/20 ISL campaign in 5th place, just missing out on the final play-off position.
Mumbai City did put up a fight but Goa were clinical enough to notch up an emphatic win.
Off the field, the Kolkata fans easily outshouted the Mumbai supporters. On it, ATK comfortably outplayed Mumbai City FC.
Football association suspends Mumbai City FC U-18 team, slaps Rs 10 lakh fine for assault on official
Goalkeeping coach Abdul Qadeer, physio Jay Singh, coach Mohan Das, assistant coach Suprith Jathana and 10 players have been suspended and fined.
It was ATK captain Roy Krishna who capitalised on a defensive lapse to score from probably the last kick of the game.
Mumbai refused to sit back and let Goa pass the ball around in the opening minutes but the hosts, however, failed to test Mohammed Nawaz's goal during that period.
Mumbai City FC played five pre-season games and will start their campaign with a game at Kochi against Kerala Blasters on October 24.
After three matches without a goal, Modou Sougou (26', 39', 60') returned to the scoresheet with an excellent performance.
The 24-year-old custodian joined Mumbai City FC for the 2016 season of the ISL, initially on loan from Bengaluru FC.
Edu scored in the 67th minute off a set-piece movement while Chhetri cashed in on a defensive blunder from Mehrajuddin Wadoo in the third minute of stoppage time.
The league has been extended for two more months, being played over five months instead of the earlier three, with the coming of two more sides.