Liam Hearn scored four times as Grimsby easily defeated nine-man Alfreton.
Paul Clayton fired into the top corner to put the Reds ahead, but two clinical finishes and an effort from 20 yards from Hearn put Grimsby in control.
Alfreton had James Ellison and Drewe Broughton sent off for separate violent conduct offences before Hearn's fourth came via a shot from 12 yards.
Nathan Jarman scored a penalty for the Reds after Anthony Church's foul but an Anthony Elding header sealed the win.
Hearn only joined Grimsby in June from Alfreton after scoring 32 goals for the Reds last season.
VIEWS FROM THE DRESSING ROOM
Grimsby Town joint manager Paul Hurst told BBC Radio Humberside:
"I'm delighted with the result. Liam Hearn will grab the headlines and to score four is a good achievement, particularly sweet I'm sure against his former club but it was the icing on the cake of a good performance.
"Going one goal behind is certainly not part of our team talk before the game and maybe on another day we'd have struggled to get back in front.
"With the heat, we thought that would play into our hands because it drains the players but we felt it would drain them more and it certainly looked that way as we got stronger and stronger.
"I didn't see either (red card incident) but what I would say is that Gary Silk has lost his tooth and Bradley (Wood) has got a bloodied mouth."