A brave effort by the Reds almost grabbed a point at Blundell Park - only for two late Grimsby goals to seal their fate.
The teams traded goals in the first half before that dramatic finale saw the result swing the way of the Mariners, thanks to Craig Disley and Andy Cook in the closing minutes.
Straight from the start of the match, balls over the top of Stephen Wright set first Lenell John-Lewis and then Connor Jennings away at goal.
The second of which saw Andy Coughlin forced into a good save from the ex-Macc striker, with a follow up cross being headed wide of the Wrexham goal at the back post.
A right wing cross for John-Lewis saw the big man somehow miss from eight yards, lifting his effort over the bar when in a great position to score!
A Grimsby 25-yard free kick by Sam Hutton found its way through the Wrexham wall and forced another save from Coughlin, going down low to his left.
Then at the other end a Wrexham throw in from Steve Tomassen saw Rob Ogleby head the ball on and it was a move that almost fooled James McKeown in the home goal, who only grabbed at it on his line.
Shortly afterwards Dean Keates tried a dipping volley from distance and effort that just cleared the Grimsby crossbar.
The home side went ahead on 22 minutes, when Scott Neilson outpaced Steve Tomassen down their left channel and then fired a low shot wide of the advancing Coughlin to open the scoring.
On 32 minutes, Joe Anyinsah won the ball in midfield and broke away with Ogleby and Hunt in support, but retreating defenders eventually managed to clear the danger as the ball just won’t sit up for a shot.
Grimsby were constantly dangerous on the attack and when Wright took a hand in the face, they broke through again, but Neil Ashton puts his body on the line to deny Craig Disley.
Two minutes before the break and Wrexham pulled level as Johnny Hunt’s cross from the left was deflected off centre back Shaun Pearson, wrong footing his own keeper.
A Grimsby corner on 53 minutes saw John-Lewis with a free header from 10 yards but his effort went straight into the arms of Coughlin.
Another save by Coughlin as he tipped away an angled shot from Alex Rodman, going low to his right.
Wrexham’s first substitute was Brett Ormerod on for Anyinsah on the hour.
We failed on several occasions to clear the ball after 67 minutes and it all ended with Neilson heading over the crossbar when well placed!
Carrington did hit the cross bar from distance, but a flag was up for offside anyway – a decent effort though.
Grimsby went close from another corner on 76 minutes, as centre back Andrew Boyce flashed his header wide when well placed.
With nine minutes left Jay Harris was introduced for Ogleby, to try and reinforce the centre of the park.
Just when it looked like we might get a draw, the home side swung over a deep cross from Aswad Thomas on their left and Craig Disley rose highest to get his head on the ball and hammer it passed Coughlin on 87 minutes.
Dave Artell was thrown on as we entered added time to try and salvage something by adding his presence up front, but with men committed forward it was Andy Cook who found space to beat his maker and fire across Coughlin deep into time added on.
Grimsby Town: James McKeown, Sam Hatton, Andrew Boyce, Shaun Pearson, Aswad Thomas; Alex Rodman (Paddy McLaughlin 89), Andy Thanoj, Craig Disley, Scott Neilson; Lennell John-Lewis (Andy Cook 72), Connor Jennings (Ross Hannah 86).
Subs: Scott Kerr, Paul Bignot.
Wrexham: Andy Coughlin, Steve Tomassen, Stephen Wright, Danny Livesey, Neil Ashton; Mark Carrington, Joe Clarke, Dean Keates (David Artell 90), Johnny Hunt; Rob Ogleby (Jay Harris 81), Joe Anyinsah (Brett Ormerod 59).
Subs: Joslain Mayebi, Danny Reynolds.
Referee: Jason Whiteley (Yorks)
Grimsby: Neilson (84 foul), Hatton (90 foul)
Wrexham: Ormerod (82 time wasting)