A last-minute header ended Fordham’s remaining cup interest on Saturday.
Fordham found themselves a goal down at the break after Dale Archer, the club’s first-team leading scorer, headed home midway through the first half.
Alex Theobald equalised before the hosts took the lead through Reece Theobald’s deflected drive.
Granta scored two further goals, including another for Archer, before Alex Theobald levelled late on.
However, with extra-time looming, Granta struck a dramatic winner.