Carl Winchester rescued a draw for Oldham with an injury-time equaliser at Port Vale's, Vale Park.
Port Vale had come from behind when Rigino Cicilia fired in on 78 minutes, after Remie Streete had cancelled out Oliver Banks' early second-half opener for Latics.
Banks broke the deadlock three minutes after the break when a right foot 20-yard free-kick took a wicked deflection off the Vale wall to wrongfoot Alnwick.
Port Vale took levelled three minutes later when Streete headed home Ryan Taylor's free-kick and looked to have won it when Latics keeper Connor Ripley turned away Alex Jones' shot, only for midfielder Quentin Pereira to pull the ball back in from the left, allowing fellow sub Cicilia to hit home from 15 yards.
But in the dying minutes Winchester struck from close range to send the Oldham faithful into raptures on a freezing cold night in the Potteries.