Goals from former Spireites Kane Drummond and Mike Fondop did the damage in the first-half, with the dominant visitors deservedly in front.
The Blues made a triple change at the break but Drummond grabbed his second goal and Oldham’s third with less than 20 minutes remaining, which was the cue for many home fans to head for the exits.
Here are our player ratings from the game...
13. Kyle McFadzean 5
Kyle McFadzean 5 Replaced Dunkley at half-time. Left exposed for the third, with Drummond tapping in behind him for the third. Photo: Tina Jenner
14. James Berry 5
James Berry 5 Came on half-time and took up his usual wide left position. Had some bright-ish moments. Photo: Tina Jenner
15. Malik Owolabi-Belewu 5
Malik Owolabi-Belewu 5 On for Duffy at left-back at half-time. Photo: Tina Jenner
4 / 4