Despite adding to his squad earlier in the day by signing central defender Simon Downer and midfielder Abdou Elkolti from Weymouth, Grays boss Justin Edinburgh chose to play a young and inexperienced side in Tuesday's Essex Senior Cup quarter-final.
Braintree, who were also at less than full strength, had former Grays striker Bertie Brayley leading their attack and he almost pulled of a late escape for the visitors, who had gone behind to a 55th minute header from Ashley Barnes, striking the upright four minutes from the end with a shot from 20 yards. The rebound was put into the net by James Baker but he was offside.
Grays, whose squad changes also include the release of central defender Nathan Moulds, had earlier suffered a blow when new striker Aaron O'Connor limped out of the action in the first half, to be replaced by matchwinner Barnes.
The Grays squad featured brothers Luke and Michael Woodward, who was making his first team debut, who are the sons of chairman Mick.
They, along with several 17-year-olds performed well through on a night when, apart from O'Connor's injury, the only downside was a late injury to Jamie Nelson who was stretchered off after a shocking challenge from Ashley Harewood, for which the Braintree player was lucky only to get booked.
Grays now join Aveley, AFC Hornchurch and Great Wakering Rovers in Wednesday's semi-final draw.
Thanks to the Thurrock Gazette for the report.