Charles Vernam’s penalty gave the Mariners a hard-earned victory over nine-man Gillingham at Blundell Park.
Town were on top for the majority of the contest but they were largely frustrated by a well-organised away defence, who ensured they remained in the game despite their numerical disadvantage.
Both teams created chances in a goalless first half but the hosts had the momentum after Remeao Hutton was shown a straight red card.
And the breakthrough came two minutes before the hour, as Jaze Kabia was brought down inside the box and Vernam stepped up to score from the spot.
Midfielder Jonny Williams was also dismissed soon afterwards for a second bookable offence to leave Gillingham down to nine men for the remainder of the game and Town poured forward in search of more goals but despite their pressure, one proved enough to seal maximum points.
Grimsby head coach David Artell made three changes to the team that started last week’s 2-1 home defeat by Colchester United, with Sam Lavelle, Justin Amaluzor and Jamie Walker coming in for Tyrell Warren, Darragh Burns and Evan Khouri.
Christy Pym started in goal, as Harvey Rodgers, Cameron McJannet and Jayden Sweeney joined Lavelle in the back four. George McEachran lined up behind Amaluzor, Kieran Green, Walker and Vernam in midfield and Kabia led the attack.
Warren and Khouri were both named on the bench, alongside Charlie Casper, Jason Svanthorsson, Clarke Oduor, Danny Rose and Jude Soonsup-Bell.
Gillingham made the journey north from Kent sitting third in the Sky Bet League Two table, three places but just one point ahead of the Mariners at kick-off.
With manager Gareth Ainsworth recovering after a heart operation, assistant boss Richard Dobson led a team which included former Town loanee centre-back Andy Smith.
FIRST HALF
Josh Andrews headed over the bar at the far post after an early Hutton long throw was not fully dealt with, then Green linked up with Amaluzor to create Town’s first opening but the ball ran through to Gillingham goalkeeper Glenn Morris.
Verman won the game’s first corner on the home left and after the winger’s delivery was cleared back to him, he cut inside and fired a curling shot from 20 yards which was caught by Morris.
Seconds later, the visitors had a great chance to open the scoring as Seb Palmer-Houlden beat Sweeney to Morris’ long kick to go through on goal but Pym stood tall to block his shot for a corner.
Neither side had gained control of the game over the course of a lively opening 10 minutes, although both were creating openings and Town’s latest saw Kabia shoot just wide with a low effort from the edge of the box.
Rodgers picked Vernam out at the far post with a cross from the right and he looked for Kabia with a header back across goal but the visitors cleared.
Vernam then worked the space for a low cross from the left on 15 minutes as Town started to get on top but defender Max Clark got to it ahead of Green and Morris dived on the loose ball.
McJannet intercepted a low cross from Sam Gale after a run down the away right, before a ball into the box at the other end from Vernam was eventually cleared as Green and Kabia both aimed to profit.
Kabia saw the first yellow card of the afternoon on 27 minutes for a foul on Gale, before Walker linked up with Sweeney to create an opening but was unable to get on the end of the left-back’s return ball into the box and Gale got back to win a goal kick.
Rodgers headed a Bradley Dack free kick behind for an away corner but Gillingham were unable to turn it into a chance in front of goal.
Soon afterwards, a potential turning point came as the visitors were reduced to 10 men when Hutton brought Kabia down midway inside the Gillingham half after the striker got to a long ball first. The referee ruled it to be denying a clear goalscoring opportunity and brandished a straight red card.
A low cross from Vernam was cut out before it could reach Kabia after an intelligent through-ball from Walker created an opening on the Town left, then Williams blocked a 20-yard strike from Rodgers as the hosts looked for a breakthrough before the interval.
Morris got down to push a low shot from Vernam away from danger but the home side kept coming forward and Smith cleared crosses from Rodgers and Amaluzor.
Walker missed the target with a curling effort from the edge of the box as the first half moved into a minimum of three added minutes, then after a Gillingham long throw was dealt with, Sweeney won a corner on the Grimsby left. Vernam’s delivery was headed back to him and when a McEachran cross was headed away, the referee blew for half-time with the score still goalless.
SECOND HALF
No changes were made before the restart and Town had the ball in the net within a minute as Kabia finished from close range after Morris got fingertips to Vernam’s header. The striker’s celebrations were cut short though, as the offside flag went up against him.
Green was booked on 50 minutes, then McEachran saw a shot blocked after getting on the end of a Vernam cross and a deflection on a shot by Walker took the ball over the bar.
Rodgers saw the yellow card after an incident near the edge of the Gillingham penalty area but the next time Town went forward, they were given an opportunity to finally make their pressure count, as Kabia was brought down inside the box by Gale. The referee pointed to the penalty spot and VERNAM stepped up to beat Morris and open the scoring.
The away side responded by swapping their strikers in a double-substitution, as Sam Vokes and Elliott Nevitt replaced Andrews and Palmer-Houlden.
Town were firmly in charge now and they pushed forward in search of a second goal, with Green heading just wide and Walker curling a shot off-target from the left.
The visitors’ task was to get tougher on 63 minutes as they were reduced to nine men. Williams, who had been booked for a foul three minutes earlier, saw a second yellow card for pulling Rodgers down.
Armani Little replaced Dack after the sending-off and after Ethan Coleman was booked for a foul, the substitute quickly followed him into the referee’s notebook for delaying the resulting free kick.
Morris dived to deny Green after the midfielder linked up with Amaluzor at the end of a well-worked Town move and the chances continued to come, as Morris dived on the ball from Amaluzor’s flick after the winger was found by McEachran.
Vokes was unable to profit when a free kick broke for him in a rare attack by the visitors but Town were still in control and McEachran sent a shot just wide from distance.
Soonsup-Bell and Khouri came on for Vernam and Walker in the Mariners’ first changes with 10 minutes to go, then Green fired a volley wide from inside the box as Town kept looking for a second goal.
Rodgers was just off-target with a low shot after Gale became the latest to be booked and the yellow card was soon out again, this time for Clark following a foul on Amaluzor.
Morris caught a shot from Amaluzor, before Shadrach Ogie replaced Clark in the visitors’ latest change.
Kabia made way for Rose with two minutes remaining, then there was a chance for Gillingham to get the ball into the Town box from a free kick just inside the home half. Morris found Smith but he could only head through to Pym.
The visitors won another free kick inside the Town half for a foul by McJannet as the game moved into at least seven added minutes but again, they were unable to make the most of it.
Gillingham pushed forward in search of an unlikely equaliser but the referee waved Nevitt’s appeal for a penalty away when he went down inside the box.
And when another free kick ended with the ball in Pym’s arms, the final whistle blew to seal all three points for the Mariners.
Town are next in action on Saturday, when they travel to Crewe Alexandra.
Town: Pym, Rodgers, Lavelle, McJannet, Sweeney, McEachran, Amaluzor, Green, Walker (Khouri, 80), Vernam (Soonsup-Bell, 80), Kabia (Rose, 88)
Subs not used: Casper, Warren, Svanthorsson, Oduor
The official attendance, brought to you by the Kingsway Hotel Cleethorpes was 6,659.
UTM