Colchester United closed the gap to the top seven to just two points on Good Friday, as a first half Frank Nouble goal was enough to secure a crucial victory.
The U's could have been out of sight in the first half, with a flurry of chances in the opening forty-five minutes in an impressive performance.
Grimsby saw more of the ball in the second half without truly threatening Dillon Barnes in the Colchester goal, as they recorded another clean sheet.
And so the U's hopes of the play-offs remain very much alive, ahead of the final three games of the campaign.
It was a strong start to the game and the U’s had four chances in three minutes to open the scoring.
First, Dickenson forced a good save out of the keeper from a free kick and, from the resulting corner, Eastman had a header cleared off the line by Grayson.
The U’s then saw Nouble and Senior combine on the edge of the box, with the latter cannoning a shot off the base of the post.
And the pressure was unrelenting, with Nouble setting up Saunders to have a shot that was deflected inches wide.
After that spell, the U’s didn’t see the ball for five minutes, but went close again on 22. Great work from Nouble set it back for Senior, but he leaned back and fired well over.
Having set up Senior twice, Nouble got on target himself on 25 minutes after good work by Szmodics. He unselfishly squared it and Nouble calmly finished past McKeown.
Ten minutes later and he nearly got his second, as Szmodics’ strike was spilt by the keeper but it ran just past Nouble as he followed up.
As the half drew to a close, Szmodics showed fantastic work rate to get the U’s away from trouble and then set Jackson away. His shot was lifted well over, at the end of his good run.
The U’s had enjoyed a strong first half display, and nearly got a second within three minutes of the restart, as Eastman headed a corner back into the danger zone and Kent’s hooked effort was cleared off the line.
The visitors started to grow into the game, though, having a couple of corners to test the U’s defensive mettle.
And Barnes had to parry a dangerous Hall-Johnson cross away from danger as the Mariners started to threaten.
The U’s made their first change with twenty minutes to go, as Mandron was introduced in place of Dickenson.
And their second change came with ten minutes to go, as Eisa replaced Senior.
The U’s then stepped it up a gear, with McKeown standing strong to deny Szmodics after Saunders’ pass, and Eisa rippling the side netting from a shot on the angle.
The U’s introduced Stevenson for Szmodics as injury time got underway, and they saw out the additional time with little worries.
It wasn’t so good for the visitors, though, as captain Collins was sent off for two bookings in injury time.
And it meant a crucial three points for the U’s, keeping their play-off hopes alive ahead of Monday’s trip to Huish Park.