Macclesfield handed Northampton an early Christmas present with a slipshod defensive display that allowed the Cobblers to score three second half goals.
Having played out a first half stalemate, Northampton capitalised on Macclesfield's growing frustration. The opener came in the 50th minute when French striker Eric Sabin caught Graham Potter too far forward. His defence-splitting pass was latched on to by Josh Low, who neatly chipped into the far corner.
Macclesfield then laid siege to the Northampton goal with Paul Harsley warming the fingers of Lee Harper.
They were back on level terms in the 64th minute. Former Manchester City striker Mike Sheron met a Harsley corner with a powerful downward header which Harper could only shovel into the path of Potter, who gleefully poked home from close range.
Macclesfield might then have taken a grip on the game as Sheron met another Harsley corner with a powerful half volley that fizzed past the post.
But Macclesfield were caught cold in the 76th minute whan a Matt Carragher clearance fell to the feet of Charlie Hearn. The on-loan midfield man took aim and saw his drive deflected past the wrong-footed Steve Wilson.
Worse was to follow for Macclesfield as Michael Welch tried to play the ball out of defence in the 86th minute, only gifting it to Scott McGleish who squared for Low to seal the game with his second goal, an accurate low strike into the far corner from 12 yards.
Macclesfield had opened brightly with both Jon Parkin and Sheron creating early chances, but both efforts from the edge of the box went agonisingly wide.
Before the break the strike partnership again got into pole position, but neither could find a finish.