The 35th-minute sending off of striker Lenell John-Lewis swung the match in the hosts’ favour, after the Mariners had dominated the opening exchanges.
And Brett Williams’ second half brace ensured the three points stayed in Hampshire, despite Scott Neilson’s late strike sparking a spirited Mariners’ comeback.
There were no changes to a Grimsby starting XI that had racked up 13 goals in two games over a successful Bank Holiday period, although striker Ross Hannah did return on the bench from injury, he replaced the departed Alan Connell.
It was no surprise that the Mariners were brimming with confidence and they knocked the ball around the pitch well in the first passages of play and they should have taken the lead on three minutes.
Neilson jinked his way into a good position and pulled the ball back for Craig Clay, inside the area. The midfielder had proven to be a deadeye in scoring a pair against Alfreton but he was off target this time, leaning back to fire over the crossbar.
Undeterred, the Mariners continued to push their opponents back and it was John-Lewis who was proving to be the main threat.
Clay turned provider with a neat ball into the inside left channel on 19 minutes. John-Lewis controlled superbly with his right foot but there was an unfortunate ricochet off his left boot whilst in full stride and the chance was gone.
On 27 minutes the Town frontman did force home stopper Phil Smith into a save. Carl Magnay clipped a long ball down the left that was controlled by the Mariners’ striker, who swivelled and fired in a stinging drive that the Shots’ ‘keeper turned around the post.
From the corner, Smith did well to punch away under pressure and the home side broke at pace to fashion their first opening of the game.
Mark Molesley and Kieron Forbes combined well down the right before switching the play for the run of Jordan Roberts, in space on the left.
But the Shots’ defender was closed down by the back-tracking Shaun Pearson, who did superbly to nick the ball away from danger.
A minute later John-Lewis was booked for persistent infringements and within six minutes that would prove to be costly for Paul Hurst’s men.
In between those two yellow cards the Mariners really turned the screw and should have been at least one in front.
Just after the half-hour, the Mariners created a fantastic opening. Scott Brown found himself in space on the right-hand edge of the box. He clipped an inviting ball to the far post for Jon-Paul Pittman and the former Wycombe man cushioned a header back into the path of strike partner John-Lewis. He flung himself full-length at the ball but couldn’t get a strong enough contact on the ball to divert it past Smith.
From their next attack, John-Lewis came even closer to giving his side the lead. Paddy McLaughlin swung in a free kick from the right-hand side, which was met by a cute, glancing header from the Mariners’ striker and he was unfortunate to see the ball hit the post.
Pittman was then played through down the channel and, like in Monday’s game, he rounded the goalkeeper. But the angle was narrower than his goal against Alfreton and when he got his shot away there were defenders back to cover.
From the restart the game changed after a sliding challenge from John-Lewis. The big striker was looking to press in the middle of the park and his innocuous tackle was adjudged to be a second yellow card by referee Whitton.
And there was a further blow for Town within two minutes when McLaughlin was forced off with a bleeding mouth, which temporarily reduced Hurst’s side to nine men.
The Shots enjoyed a long spell of possession before the break but they only had a harmless shot from Forbes to show for their efforts.
Instead, Andy Scott’s men seemed intent on getting more Mariners into the book. Dan Fitchett was the main culprit, clashing with Magnay on the right but as the home fans voiced their disapproval, the assistant referee flagged for a free kick in Grimsby’s favour.
The two sides went in level at the break but the Mariners’ players were aggrieved and James McKeown, Toto Nsiala and Brown let the officials know their thoughts as they went down the tunnel.
The officiating infuriated the visiting fans even further at the start of the second half. Pearson was booked for kicking the ball away, when in all probability he had not heard the whistle sound.
Nsiala was given another talking to but when Neilson was pulled back cynically by substitute Tony Tomkin, the Shots’ defender was not even spoken to by referee Whitton.
The ten-men Mariners almost took the lead from the resulting free kick though. The ball eventually worked its way through to Pearson at the far post but he could only lift his floating effort onto the top of the net.
Pittman then got in on the left channel, where the Mariners were enjoying most freedom, and he waited patiently to pull the ball back for Clay. The former Worksop man laid the ball off for Brown, who fired in a 25-yard shot that fizzed just over the crossbar.
Within a minute the visitors were dealt a hammer blow when Williams fired the home side in front. Top scorer for the Shots last season, the striker was on hand to slot home Fitchett’s pull back from the left-hand side.
Nsiala was unhappy with the manner of the goal but he received short change from the referee and was ordered from the field to deal with another bloody Mariners’ mouth.
Scott’s men were fully on top now and McKeown had to be at his best to deny Williams a second when the striker was left unmarked eight yards from goal.
But the Mariners were not so fortunate on 64 minutes when Williams did net his and his side’s second. Pearson hesitated from a long clearance and the Shots’ striker was on it in a flash, hammering home from 15 yards to put his team fully in control of the fixture.
A home player finally went into the book on 68 minutes when Forbes was cautioned for a late challenge on Pearson but when Williams went down in the box trying to win a penalty, the referee again felt no need to even talk to the Shots’ player.
Hurst responded with three substitutes in three minutes as Paul Bignot, Hannah and Jack Mackreth replaced Nsiala, Pittman and McLaughlin but it was Neilson who was doing his best to push the Mariners forward and his goal on 78 minutes halved the arrears and set up a dramatic final quarter of an hour.
There appeared to be little danger when Tomkin shepherded a long ball and turned to clear down the field. But he didn’t get much purchase on his effort and it fell perfectly for Neilson to fire a wonderful 30-yard volley over the stranded Smith.
Neilson then set up Clay after another mazy run on 82 minutes. The Town midfielder worked an opening but couldn’t squeeze his shot in at the near post.
Manager Hurst moved both Neilson and Pearson up top as the game moved into the final five minutes – the Mariners deploying a 3-3-3 formation in the search for what would have been a deserved point.
But they could only forge one good opening and it came in the last minute via substitute Mackreth. The winger beat his man down the right and cut inside but his left-footed effort curled agonisingly wide of the far post.
The final whistle blew after four minutes of injury time and Hurst’s men were left questioning the impact the officials had had on a game that they look destined to win with their full quota of eleven men.
Shots: Smith; Gibbs, Oastler, Wilson, Roberts; Molesley (N’Guessan), Lathrope, Forbes, Hatton (Tonkins); Williams, Fitchett (Derry). Subs not used: Plummer, Thomas.
Mariners: McKeown, Nsiala (Bignot), Pearson, Boyce, Magnay; Neilson, Brown, Clay, McLaughlin (Mackreth); Pittman (Hannah), John-Lewis. Subs not used: Disley, Winfarrah