Lee Hughes' 22nd goal of the season brought Notts County the points at Grimsby.
The striker hammered home in the 69th minute to consign Grimsby to a club record 20th league game without a win.
Ricky Ravenhill was in the thick of the first half action. The County midfielder tested Nick Colgan with two volleys and then sent a third inches wide.
But he blotted his copy book with a yellow card for a two-footed tackle on Peter Sweeney and was fortunate not to be sent off after hauling back Wes Fletcher.
Grimsby's Tommy Wright headed over the bar from a Sweeney corner and then the striker was booked for a two-footed lunge on Neal Bishop.
The crucial goal came from a long clearance from keeper Kasper Schmeichel which was missed by centre-back Paul Linwood. Hughes raced clear and hit a right-foot shot into the far corner.
Grimsby went close to an equaliser when an overhead kick from substitute Nathan Jarman was clawed away by Schmeichel.
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