Two-goal Francis Green fired Macclesfield Town into the prospect of third round riches and dealt a devastating blow to cash-strapped Port Vale's finances.
Vale Park was shrouded in fog, but the visitors, who arrived with memories of a 4-1 victory on this ground in September, were soon in the ascendancy.
They penned Vale in their own half and the early pressure brought the opening goal in the ninth minute.
Martin Gritton's headed flick found Green and he spun his marker Gareth Owen to bury a ten-yard shot low inside Joe Anyon's left-hand post.
The goal shocked lacklustre Vale into life and Louis Dodds should have done better than fire his shot wide after the trickery of Paul Edwards created the chance.
But Macclesfield were in no mood to be pushed back and Gritton almost applied the finishing touch after a mistake by Damien McCrory allowed Green to break free.
Vale came close to the tonic they desperately required when Dodds cut inside to bend a splendid effort against the crossbar two minutes after the half-time break.
And the contest started to really open up with Gritton forcing Anyon into a fine save at the other end, before Vale debutant Neil MacKenzie also went close.
The Vale fans were finally getting behind their team and a period of sustained pressure brought a deserved equaliser in the 71st minute.
Fittingly it was Dodds who made no mistake with a close-range shot after substitute Danny Glover had clipped in a low cross from the left.
But an awful back-pass by Vale substitute Luke Prosser sent Green racing clear for his second in the 73rd minute, before Gritton added a third in the closing seconds.
The powerful striker got the better of Vale defender Anthony Griffiths to slam a left-foot shot beyond the onrushing Anyon.