Jersey suffered a dramatic 19-16 defeat away at struggling Cinderford.
Rory Teague held his nerve to score a long-range penalty in the closing moments to seal the win for the Gloucestershire side.
Earlier a converted penalty-try and three penalties from Teague had given Cinderford the advantage.
Injury-hit Jersey, without seven first-team players, were behind for much of the match but had pulled level at 16-16 thanks to a Michael Le Bourgeois try.
The youngster claimed all the points for the islanders.
Jersey drop to 10th spot in National One while Cinderford climb off the bottom of the table to 13th.