Rory Fallon and Tommy Mooney started to game leaving top scorer Sam Parkin on the bench.
Swindon 1 Oldham 2
Paul Murray gave Oldham the lead after only 8 minutes with a curling 25 yard shot with left Evans with no chance to save it.
Oldham were having a lot more of the ball during the first half, with Swindon not really having any good chances, instead just being restricted to the odd long shot.
In the second half Swindon were slightly better than in the first half, with Sam Parkin coming on to replace Andy Nicholas.
Oldham made it 2-0 after 71 minutes when Jermaine Johnson looked to be offside, but beat Evans with a good shot from 20 yards out.
Rory Fallon made it 2-1 after 79 minutes with a close range goal, but despite a few late chances it wasn't enough for Swindon to get anything out of the game.
Overall a poor game by Swindon, in which if they had win the would have confirmed at least a place in the play off's, and still would have had a chance at getting second spot, Swindon's next game is a trip to West London next Saturday to play QPR.