Former Barcelona B striker Salva Chamorro (2', 21') scored the two goals in the opening half and it was enough for Bagan to start their campaign on a winning note.
Kibu Vicuna fielded his team in a 4-4-2 formation with veteran custodian Shilton Paul under the sticks. He was shielded by Ashutosh Mehta, Fran Morante, Gurjinder Kumar and Dhanachandra Singh in a back four. Spaniard Joseba Beitia anchored Mohun Bagan's midfield along with academy graduate SK Sahil. Nongdamba Naorem and Surabuddin Mollick occupied the left and right flank respectively with Chamorro leading the attack.
Bagan got off to a flyer as they drew first blood as early as the second minute through Chamorro. Beitia floated in an inch-perfect free-kick and the Spanish striker rose the highest to deflect the ball into the net with his head.
The Mariners continued to dictate the momentum of the match with Beitia controlling proceedings from the centre of the park. The 28-year-old midfielder aced in his role as a playmaker and the opposition midfielders had a tough time containing him.
Although Vicuna handed starts to nine fresh faces, the team looked well-drilled. In the 21st minute, they doubled their lead and it was Chamorro once again who made a difference. Mollick released Mehta with a through ball on the right flank and the latter fired in a first-time cross. The 29-year-old looked unbeatable in the air as he once again jumped higher than his marker Omolaja Nurain to score his second goal of the day.
Subrata Bhattacharya's men tried to claw back into the game after falling behind by two goals but the midfield duo of Beitia and Sahil denied space to the opposition.
Just at the nick of half-time, Arthur Kouassi could have pulled one back for Mohammedan but his point-blank header was denied by a diving Paul.
After the break, it was Amir Hossain who had the first sight of goal but Paul was on his toes to negotiate with it at the expense of a corner. But Mohun Bagan soon took control of the match and Mohammedan lacked creativity in the attacking third.
Mohun Bagan will be back in action on Monday in the Calcutta Football League against Peerless SC whereas Mohammedan Sporting will take on Aryan Club in the same competition on August 7.