A goal from young Lalrindika Ralte in the 111th minute saw East Bengal beat Churchill Brothers 1-0 after extra time in Siliguri and reach the Federation Cup final for the fourth consecutive edition.
Both teams struggled to create openings in regulation time but East Bengal looked more eager to break the deadlock with strikers Edeh Chidi and Manandeep Singh going close.
Churchill Brothers skipper Beto couldn't play his natural game as he was hardly given any time and space and as a result the Goan club never looked like scoring.
The substitutions of Trevor Morgan in the second half made a big difference as East Bengal ended the 90 minutes stronger.
But it was the introduction of Ralte that proved to be decisive as the Mizoram medio found the winner with a left-footed half volley after getting on the end of a Chidi header.
Churchill Brothers midfielder Israil Gurung was also sent off for an off the ball incident.