In group A matches in Jamshedpur, Dempo rode on a Clifford Miranda strike (45th) to down Shillong Lajong by a solitary goal at the JRD Sports Complex.
In another match of the same group simultaneously played at Keenan Stadium, AIFF developmental outfit Pailan Arrows put up a spirited show to hold Mumbai FC 2-2.
The Mumbai outfit struck through N D Opara's twin-goal effort (12th and 62nd) but the Kolkata-based outfit negated the effort with strikes from D Ganesh (45th) and Deepak Devrani (78th).
It was disappointing first day for East Bengal as last year's runners-failed to log full points and were reduced to 10 men after their inspirational playmaker Mehtab Hossain was sent off three minutes before the regulation time.
Edeh Chidi gave the red and golds the lead converting a spot kick in the ninth minute but Victorino Fernandes equalised for the Goan outfit in the 82nd minute.
Hossain got marching orders after he got double booking during the fag end of the match.
Earlier in the day, ONGC routed qualifiers Kalighat Milan Sangha 5-1 in another group C match at the Kanchanjunga Stadium in Siliguri.
Having returned to winning ways, Dempo lead group A with four points from two matches, followed by Shillong Lajong (three points), Pailan Arrows (two) and Mumbai FC (one).
In group C, ONGC are placed on the pole position with three points, while East Bengal have one. Kalighat and Sporting Clube de Goa are yet to open accounts. MORE
