Danny Whitehead's last-minute winner helped Stockport come from behind to record a dramatic victory over Grimsby.
Danny Hattersly headed wide for the Hatters in a lacklustre first half.
Indeed, it was not until well after the break when Nathan Pond put the hosts ahead with a crashing volley into the top corner.
But Danny Rowe hit back with a crisp strike from 18 yards late on, before Whitehead found the back of the net from inside the area at the death.
VIEWS FROM THE DRESSING ROOM
Grimsby Town joint-manager Paul Hurst told BBC Radio Humberside:
"Obviously we're disappointed, we got ourselves in front like we did on Saturday and then to lose the game is a bit of a travesty.
"But we look at ourselves and we're disappointed with the bad goals we gave away and whether Stockport deserve the win or not, that's what they go home with.
"We have to improve, that's two games already we've dropped points from winning positions.
"We wanted to keep taking the game to them and for some reason we struggled to get hold of the ball."
Grimsby Town 13 McKeown 03 Thomas 05 Pearson Booked 04 Niven Booked 07 Colbeck 08 Disley 11 Artus (Soares - 83' ) 19 Wood 22 Pond 12 Cook (Elding - 58' ) 18 Pearson (Hearn - 58' ) Substitutes 02 Hatton 16 Ford 17 Soares 09 Elding 10 Hearn Stockport County 01 Ormson 02 Halls 03 Newton 05 O'Donnell 06 Tunnicliffe 04 Connor 08 Kenyon 18 Nolan 09 Hattersley (Whitehead - 74' ) 11 Hobson Booked (Piergianni - 59' ) 19 Rowe (Darkwah - 85' ) Substitutes 21 King 15 Piergianni 20 Fagbola 07 Whitehead 13 Darkwah