Three first-half goals earned the points for the visitors, with Antoni Sarcevic opening the scoring, before Isaac Olaofe made it 2-0.

Both teams had goals ruled out for offside, with Olaofe seeing his celebrations cut short for Stockport before Gavan Holohan also saw the assistant referee’s flag following a neat finish from a Denver Hume cross which would have halved the deficit.

Instead, Stockport went on to add a third before half-time through a Lewis Cass header.

Town were much-improved after the break and they pulled a goal back when Abo Eisa struck from close range, although the visitors saw out the remainder of the contest to ensure there would be no comeback.

The Grimsby team was unchanged from the XI that started last week’s goalless draw at Accrington Stanley, with Liam Smith, Hume and Curtis Thompson all making their home debuts after impressing in Lancashire.

Goalkeeper Harvey Cartwright was protected by a defence of Smith, Harvey Rodgers, Niall Maher and Hume, with Thompson behind Arthur Gnahoua, Holohan, Harry Clifton and Eisa in midfield as Danny Rose led the attack.

The home substitutes were Jake Eastwood, Kieran Green, Rekeil Pyke, Charles Vernam, Jamie Andrews, Justin Obikwu and Toby Mullarkey.

Stockport made the journey east looking to at least maintain their four-point lead at the top of the league table, with top scorer Olaofe aiming to add to his 15 goals so far this season.

A searching ball from Hume through the middle proved just too far ahead of Holohan as Town started off on the attack, before a cross from the right was cut out for the afternoon’s first corner.  Hume’s delivery from the flag was not fully dealt with and the pressure continued with a throw-in on the left.  That led to Hume sending a great low cross over for Rose but he was caught offside as he met it.

Nick Powell could only find Cartwright at the other end after recycling a cross from Ryan Croasdale, then a foul by Clifton on Sarcevic gave the away side a free kick inside the Town half but Ethan Bristow’s ball from it was headed out for a goal kick.

The visitors took the lead on nine minutes when a short clearance from Cartwright was intercepted by SARCEVIC on the edge of the box and he produced a composed finish to clip the ball back over the advancing keeper.

A Smith free kick from halfway was caught by Stockport stopper Ben Hinchliffe as the hosts looked to respond but instead, they were to fall further behind on 14 minutes.  A quickly-taken free kick caught the Town defence out and after taking the ball forward into the box, Connor Lemonheigh-Evans squared for OLAOFE to tap into the net for 2-0.

Stockport had the ball in the net again three minutes later when Olaofe ran onto Sarcevic’s through-ball and beat Cartwright with a superb chip, although this time, the assistant referee’s offside flag had already gone up against the striker and the goal was ruled out.

The Mariners thought they had made it 2-1 when Holohan sent a flick past Hinchliffe after Eisa had chased the ball down on the left and set up a great run and pass from Hume but again, the offside flag was up to rule out what would have been a great team goal.

Callum Camps won a corner for the visitors on 27 minutes and it eventually led to their third goal.  After the danger from it was not fully dealt with and a header from Cass hit the bar, the ball was sent back into the box by Sarcevic on the right and CASS directed a header past Cartwright and into the net.

Thompson was shown the first yellow card of the game on the half-hour after a coming-together with Olaofe and Smith followed him into the referee’s notebook four minutes later for a foul.

Eisa fired wide from 25 yards at the end of a promising attack as the Mariners aimed to get themselves back into the contest, then Cartwright had to come off his line to prevent the away side from adding to their lead after a quick break at the other end led to Croasdale pulling the ball back towards Lemonheigh-Evans.

Stockport were forced into making the afternoon’ first change five minutes before the break when defender Akil Wright went down injured.  He was replaced by Neil Byrne.

Sarcevic was penalised for a foul on Clifton and Hume’s resulting free kick led to a corner on the right, although Town were unable to test Hinchliffe from the flag-kick.

Eisa lifted a shot just over the bar after working an opening on the edge of the box, before Clifton got back to make an excellent challenge and deny Olaofe at the other end as the first half moved into five added minutes.

A final opportunity for the visitors came with a corner on the right but Bristow’s delivery was headed wide at the far post.

That meant Town’s deficit remained at three goals going into the interval, with much to do in the second half if they were to take a positive result from the game.

The Mariners made a triple-substitution before the restart, with Green, Andrews and Vernam replacing Thompson, Holohan and Gnahoua.

Sarcevic was booked for a foul on Andrews, then a trip on Eisa gave Town another free kick, this time inside the Stockport half.  The ball from it was cleared at the edge of the box.

Olaofe missed the target after taking advantage of a mistake in the Grimsby defence, but the hosts had started the second half positively in attack and they pulled a goal back seven minutes in.  Vernam cut inside from the right and hit a low shot which Hinchliffe could only push into the path of EISA, who converted the rebound from close range at the far post.

Town then set off in search of a second goal and Vernam lifted a 25-yard effort over the bar after a corner from the left.

A shot by Eisa was deflected behind for a corner after more good play by Vernam, although Hinchliffe was equal to Hume’s delivery from the flag.

Eisa won a further corner when his low cross from the left was cut out and it turned into another but this time, it was played short and the away side broke, eventually winning a corner of their own after a good challenge by Hume on Olaofe.

Myles Hippolyte replaced Camps and Odin Bailey came on for Sarcevic as Stockport made a double-substitution on 64 minutes.

Cass became the latest to see the referee’s yellow card after he brought Eisa down on the halfway line, then Green was also booked after a foul on Croasdale in midfield.

Rodgers did well to get the ball away for a corner after a break by Olaofe, before a strike by Vernam was blocked at the other end after he had cut inside from the right.

Paddy Madden and Ibou Touray replaced Olaofe and Powell as Stockport boss Challinor looked to his bench again on 72 minutes, before Hinchliffe came off his line to get to the ball ahead of Green.

Hume was booked for pulling Hippolyte back on the away right and Bristow’s free kick was punched away by Cartwright to Cass, who won a corner after Clifton made a good challenge.  The referee spotted an infringement when the ball was sent across from the flag and blew for a Town free kick.

A strike from Lemonheigh-Evans was blocked by Maher for another corner on the away right but Rodgers was first to Bristow’s delivery to head clear.

Lemonheigh-Evans narrowly failed to connect with a low cross from Bristow on the left as the away side created another opening on 82 minutes.

Obikwu replaced Eisa for Town soon afterwards as they continued to look for a way back into the contest.

But they were unable to find a second goal as Stockport saw out the rest of the game, including four added minutes, to seal the points and retain their four-point lead at the top of the league table.

The Mariners are next in action on Tuesday, when they travel to Colchester United.