Vlae of White Horse beat Swindon 1-0 at Highworth Town FC in the ESFA Under 15 Inter Association Trophy to earn a second-round tie next month at home to Coventry or Cheltenham.
Swindon fielded a number of boys who are on schoolboy forms with Swindon Town.
But Vale, who played up the slope during the first half, defended superbly.
Vale's winner came early in the second half when a Swindon defender handled the ball as Joe Fleming tried to flick the ball over his head.
Matty Fitzgerald scored from the resulting penalty.
Vale goalkeeper Matt Crowther made a brilliant one-handed save to keep Swindon out.
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