East Bengal struck through Baldeep Singh's double strikes (22nd and 71st minute) and substitute Ranti Martins (75th) completed the rout to keep their slim hopes of qualifying for the knockout round alive.
The red-and-gold brigade also avenged their 1-2 defeat to the Singaporean outfit that slipped to bottom of the group F standings with three points, while East Bengal (four) jumped to third place.
Malsawmtluanga took the resultant corner as Baldeep put the ball in with a powerful header to give East Bengal the lead.
East Bengal could have easily doubled the lead after the changeover, but Baldeep made a mess of a neat through pass from Baljit Singh, fluffing in front of an open net.
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Baldeep completed his second goal after he put it across Nurullah into the top corner.
Eight minutes after he was brought in, Martins made his presence felt when he took the possession from Baldeep and fired the ball in.