Swindon Town suffered defeat at Boundary Park on Saturday afternoon as a goal in each half secured all three points for Paul Dickov's play-off chasing Latics.
An early effort from Chris Taylor put the home side ahead before a late penalty condemned Town to a 2-0 away reverse.
Town named an unchanged line-up for the game with Jonathan Douglas named amongst the substitutes on his return from a three-match ban.
It was the worst possible start for the Robins who conceded the opener with just four minutes on the clock. A cross from Filipe Morais was headed away by Paul Caddis, with the ball landing only as far as Chris Taylor who brushed off the attentions of Matt Ritchie before curling in a neat finish from 12 yards.
Charlie Austin nearly provided an immediate reply for the Robins, but his left foot shot was easily gathered by Manchester United loanee Ben Amos in the Oldham goal.
Caddis came to Swindon's rescue with a superb block inside the box to deny big striker Oumare Tounkara, who linked up well with Taylor in the early stages.
Swindon began to find their stride as the game approached the half-hour mark with Sean Morrison heading over from a Michael Rose free-kick and Alan O'Brien beginning to find space down the left hand side.
David Prutton was briefly forced from the field ten minutes from time for treatment to a laceration to his right arm after being bundled into the advertising hoardings in a challenge with Dean Furman. After several minutes of treatment the skipper returned to the field with Town still searching for the equaliser.
It was a turgid end to the half with neither side able to produce any real moments of magic.
Both teams emerged unchanged for the second half with Swindon knowing they would have to step up their game to return from Boundary Park with point - or more - from the game.
The home side had two chances to extend their advantage inside the opening ten minutes of the half with Chris Taylor and Cedric Evina both having opportunities. Taylor saw his effort deflected wide whilst Evina's low drive was blocked by Frampton.
Town boss Danny Wilson made a double switch just before the hour mark with Alan O'Brien and Michael Timlin replaced by David Ball and Jonathan Douglas.
Ball almost marked the final game of his loan spell with a goal after collecting a cross from Prutton but the Manchester City.
Just after the hour Town were dealt another injury blow with Andy Frampton forced off with Scott Cuthbert taking his place in the heart of the defence.
Matt Ritchie almost found a way past Amos with 23 minutes remaining with a cracking drive from the edge of the box which the Old Trafford graduate did well to turn behind for a corner.
Swindon came close to levelling the game five minutes from time. A foul on Ball saw Furman cautioned, before Michael Rose's powerful free-kick cannoned off the angle of post and bar.
It was an opportunity that the Robins were left to rue as moments later the home side made the game safe. Handball inside the box from a corner against Charlie Austin saw the home side awarded a penalty. Dale Stephens stepped up and fired the ball past Smith into the top corner.
Game, set and match on an afternoon where Swindon were looking to follow up the impressive win at Charlton Athletic with another positive performance. Sadly, the defeat means Wilson's men will now have to wait until the visit of Yeovil Town in seven days time to get more points on board.