A second-half penalty by David Eyres sealed a 2-1 win for Oldham in a stormy encounter at Crewe that saw the home side have Steve Foster sent off.
Carlo Corazzin fired the Latics into a 25th-minute lead by turning in David Beharall's low drive after Crewe goalkeeper Clayton Ince flapped at a corner.
Crewe fought back strongly with Oldham keeper Les Pogliacomi producing two stunning saves to deny Kenny Lunt and Neil Sorvel.
Lunt also saw a shot crash against the crossbar before the Alex levelled in the 55th minute through Rob Hulse, who forced his way in front of the pack at the near post to nod home Lunt's arrowing free-kick.
But the lead did not last as Wayne Andrews outpaced Foster and then collapsed under his challenge in the box.
Foster was booked for the incident, before Oldham skipper Eyres beat Ince from the spot despite the keeper diving the right way.
Foster was then dismissed after twice clashing with Andrews, leaving the home side little chance of ending Oldham's unbeaten run away from home.