Captain Terry Skiverton kept Yeovil in second spot after a close encounter. Paul Warne almost put the visitors ahead with a flick before Chris Cohen twice went close for Yeovil.
The winner arrived on half time when Arron Davies Davies hit a left-wing corner to the near post and Skiverton got down low to head home.
There was little between the two sides in the second half, but Yeovil almost grabbed a second when substitute Wayne Gray's header flew just wide.
Yeovil: Mildenhall, Lynch, Forbes, Skiverton (Tonkin 85),
Jones, Davies, Kalala, Cohen, Terry, Morris (Gray 52), Stewart.
Subs Not Used: Barry, Welsh, Cooper.
Goals: Skiverton 45.
Oldham: Pogliacomi, McDonald (Lomax 17), Haining, Stam,
Charlton, Liddell, Rocastle (Hall 74), Wellens, Taylor, Porter,
Warne (Wolfenden 89).
Subs Not Used: Ryan Smith, Wood.
Booked: McDonald, Charlton, Haining.
Att: 5,471
Ref: D McDermid (Hampshire).