Derby disappointment as Latics were defeated 3-1 by Preston North End.
An early goal by Chris Humphrey and two second half goals from Joe Garner gave Preston the victory, despite Gary Harkins firing Latics back into the game and Mark Oxley pulling off a beautiful penalty save.
Jonson Clarke-Harris was dismissed with over 10 minutes remaining but the result leaves Latics 18th in Sky Bet League One, three points ahead of the relegation places.
Preston got off to the best possible start, taking the lead within the opening six minutes of the game. A long ball from Jack King was superbly brought down by Humphrey and the winger controlled his finish past Oxley to put the Lilywhites ahead.
Latics seemed to respond well to going behind as they enjoyed spells of good possession but unfortunately were finding chances hard to come by.
David Worrall could possibly have done better when presented with a chance inside the area however his shot was tame and trickled wide of the goal.
Although the Lilywhites probably shaded the better of possession, neither side really managed to have a clear cut shot at goal.
North End had a chance on 40 minutes as Connor Brown was dispossessed on the edge of the area but Scott Wiseman's effort was deflected over the bar and the danger passed.
Both sides started the second half evenly matched but the introduction of Clarke-Harris seemed to lift the home support.
The striker was holding the ball up well and causing a nuisance in attack and really lifted everyone inside Boundary Park.
Korey Smith unleashed a stunning drive just before the hour mark which was superbly saved by Declan Rudd, who was putting in a superb performance for North End.
As Latics looked to be getting a hold of the game, Preston hit the home side on the counter attack and extended their lead through Garner.
The striker found acres of space inside the six yard box and after being released by Humphrey, the striker tapped home his first of the game.
The home side responded well however and Worrall went mightily close to reducing the scoreline straight from the kick off. Good work in the midfield presented the winger with a sight of goal but his shot was expertly tipped over by the goalkeeper.
Latics did have a way back into the game with 15 minutes remaining as Harkins blasted a volley past the goalkeeper. Clarke-Harris held the ball up well before sending in a dangerous cross towards Worrall. The winger steered it into the path of Harkins who volleyed excellently past the goalkeeper to reduce the arrears.
Only minutes after the goal, Clarke-Harris was dismissed for handling on the line, presenting Preston with a chance to extend their lead from the penalty spot. Garner stepped up but Oxley pulled off a superb one-handed stop to deny the striker.
That seemed to spur the home side on but they were again hit with a sucker-punch with only five minutes remaining as Garner netted his second of the game to give Preston North End all three points in the Lancashire derby.
Oldham Athletic: Oxley, Brown, Grounds, Wesolowski, Smith, MacDonald(Turner), Mellor, Lockwood, Philliskirk (Clarke-Harris), Worrall (Kissock), Harkins.
Subs Not Used: Dunfield, Winchester, Wilson, Rachubka.
Preston North End: Rudd, Keane, Laird, Clarke, Humphrey, Gallagher, Garner (Kevin Davies), Craig Davies (Beavon), King, Wiseman, Kilkenny (Brownhill).
Subs Not Used: Struckman, Hume, Buchanan, Holmes
Goals: Oldham Athletic (Harkins) 1-3 Preston North End (Humphrey, Garner, Garner)
Attendance: 6698 (2922 Visiting Supporters)