Two Preston goals in each half, including a first half-strike from ex-Latics loanee Daniel Johnson, settled the game 4-0 as Oldham lost their third straight match.
Lee Johnson left Oldham in ninth place in League One and just two points off the play-off places, and former Latics captain Dean Holden is setting his sights on promotion to the championship.
Rochdale have slipped to 12th ahead of the Peterborough battle though manager Keith Hill is hopeful the club can mount a title charge.
Oldham face sixth-placed Chesterfield on Saturday where the Latics will aim to extend their unbeaten run to 11 games in all competitions
Johnson sees a steel to his side that wasn’t there last season after comeback 2-1 win over Walsall at the weekend.
Oldham have gone nine games without defeat in all competitions, after squeezing past Barnsley in the Johnstone’s Paint Trophy on Tuesday night, as they prepare to face Walsall at the weekend
Rochdale lost 1-0 to Barnsley on Saturday and face Walsall in the Johnstone’s Paint Trophy tonight
Win ugly: Oldham’s Lee Johnson happy to swap attractive football for scrappy results in bid to become a ‘force’
Oldham up to 16th after win at weekend
‘Thanks, mate’: Rogue penalty verdicts cost us game – and ‘sorry’ doesn’t fix it, says Oldham Athletic boss
Lee Johnson disappointed at penalty decisions
The Latics will be looking for victory after midweek disappointment against Derby
The Shakers were relegated last week