Gary McDonald bagged the only goal, but Yeovil keeper Steve Mildenhall performed heroics to keep his side in the game.
At the other end, Yeovil could make little impression on a well-organised Oldham defence which gave them just one real opportunity to pull level.
Oldham are now unbeaten in five games and have regained their form after a terrible run which saw them fall from top spot to fifth place.
They almost took the lead within three minutes as Mildenhall made his only mistake by mis-kicking a clearance to striker Paul Warne.
Warne's shot from 40 yards only just missed the open goal and McDonald also went close with a first-time shot which Mildenhall did well to turn behind.
Oldham stayed on top and gained their reward on 37 minutes after midfield man Richie Wellens made a break from the halfway line and passed to McDonald, who slotted in from 12 yards.
Mildenhall made a superb stop just sixty seconds later when Chris Taylor tested him with a low drive towards the bottom corner.
It was Mildenhall again after 58 minutes as he brilliantly denied Wellens from 25 yards as Oldham looked certain to double their lead.
Yeovil's one clear chance fell to substitute Wayne Gray after he stole a yard on the home defence but pulled his shot wide from the edge of the box.
Oldham said goodbye to on-loan striker Leon Clarke, who was making his last appearance before returning to Sheffield Wednesday after scoring three goals in his five games with the Latics.