The Latics had won only once in their previous 13 league games and Yeovil had lost three in a row.
Yeovil were without midfield pair Lee Johnson (suspended) and Darren Way (injured) but they tore into Oldham from the start and both Phil Jevons and Pablo Bastianini went close.
It was 10 minutes before Yeovil keeper Chris Weale touched the ball and when Oldham took the lead in the 39th minute it was with their first direct attempt at goal.
Efe Sodje slipped on the edge of the box to allow Andy Liddell to cross from the right and Warne finished expertly from close range.
It seemed to take the wind out of Yeovil's sails.
In the second half they still pushed forward but it was with a lack of conviction and for all their pressing, Chris Day in the Latics goal didn't have a lot of real shots to save.
Yeovil skipper Terry Skiverton cleared one very dangerous situation in the 53rd minute but then joined in his attack to waste perhaps the best opportunity of the half, screwing a first-time shot wide.
It appeared to be a question of whether Yeovil could level, but in the 82nd minute a good move down the right by Oldham saw Liddell again providing the cross and Warne again the first-time finish.
The only downer for the Latics was the sending off of midfielder Paul Edwards four minutes from time for a second yellow card.