Richard Brodie was on target but leaders Grimsby were made to work for a 1-0 win over struggling Telford.
Brodie went close to breaking the deadlock in the first half, but his curled effort from the left side of the area went narrowly wide.
But Brodie only had to wait three minutes of the second half before he found the net. Joe Colbeck released the striker through on the goal and he clinically rolled the ball past Ryan Young into the bottom corner.
Mark Cooper's side battled back in the second half and Phil Trainer almost equalised with 20 minutes left but his 25-yard drive flew narrowly wide.
Jake Reid also tried his luck from outside the box but Mariners goalkeeper James McKeown saved well.
Ross Hannah should have added a second with three minutes left but his attempted chip missed the target after he pounced on a defensive error.
The miss did not prove costly as Grimsby extended their unbeaten run to 17 matches in all competitions.