Port Vale were caught napping early on as they were beaten 2-0 at Grimsby Town.
The home side were gifted the lead inside the opening minute.
A poor back pass from Mitchell Clark was seized upon by Wes Thomas.
The 31-year-old then rounded goalkeeper Scott Brown before slotting home.
The hosts doubled their lead eight minutes after the restart through former Vale striker JJ Hooper.
The result leaves the Valiants in 16th place with 14 points from 12 games.
Neil Aspin's side are back in action on Tuesday night when they play host to Burton Albion in the Checkatrade Trophy.