Conference leading scorer Liam Hearn struck a late winner as Grimsby fought back to snatch three points at promotion rivals Southport.
The home side were ahead in the 28th minute when Anthony Elding put through his own net from Karl Ledsham's corner.
Grimsby levelled on the stroke of half-time with an Ian Miller header.
Tony Gray missed a chance to win in it for Southport moments before Hearn scored his 24th goal of the season from close range in the 83rd minute.
VIEWS FROM THE DRESSING ROOM
Grimsby Town joint boss Andy Scott told BBC Radio Humberside:
"We felt that, first half, that the wind played a huge part.
"During the warm up it was blowing a gale - we said to them it's going to be a tough one.
"We didn't really use our brains in the first half, we came in at half time relieved at 1-0 down.
"We're still creating chances and that's the sign of a team that doesn't give up."