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...
9. Liam Mandeville 4
Liam Mandeville Usually one you can rely on to bring the energy but there was none in the first-half. Shifted to right-back in the second 45. Photo: Tina Jenner
10. Armando Dobra 5
Armando Dobra 5 Given little space to work in, snuffed out. Had a couple of efforts towards goal in the second 45, one over and one saved. Withdrawn on 72. Photo: Submitted
11. Will Grigg N/A
Will Grigg N/A Hobbled off before the 20-minute mark, replaced by Bonis. Photo: Tina Jenner
12. Lee Bonis 4
Lee Bonis 4 Came on for the injured Grigg in the first-half but fed off scraps. Oldham's three centre-backs were totally dominant. Photo: Submitted