Swindon boss Paolo di Canio was left licking his wounds after Macclesfield produced a strong second-half display in a 2-0 win.
acc took the lead in the 67th minute when on-loan striker George Donnelly flicked on a long ball from youngster Elliott Hewitt honing in on goal from 40 yards, before drilling a low drive through the hands of substitute keeper Mattia Lanzano.
The home side then sealed the game in the 83rd minute with a bullet drive from Ross Draper.
Di Canio was left cursing referee Steve Rushton when Swindon midfield playmaker Matt Ritchie danced past keeper Jose Veiga only to have his heels clipped.
The youngster lost his momentum but the referee waved away appeals for a penalty as he stayed on his feet.
Swindon had dominated the first half with Veiga making two important saves from Raffaele de Vita first palming a shot onto the post and then clawing wide a powerful low drive.
The Silkmen too had their chances with French youngster Tony Diagne heading past the post in the fourth minute and Donnelly heading wide in the 34th minute.