Blue Square Bet Premier promotion hopefuls Grimsby prepared for Sunday's FA Trophy final with a lacklustre display as they lost at Nuneaton.
Nuneaton broke the deadlock when Andy Brown tucked away Wesley York's unselfish pull back.
Louis Moult was then twice denied by James McKeown before half-time as the Mariners continued to struggle.
Gavin Cowan headed James Armson's free-kick into the arms of McKeown as they suffered a fourth-straight loss.
VIEW FROM THE DRESSING ROOM
Grimsby Town joint-manager Paul Hurst told BBC Radio Humberside:
"I can't pick any positives out apart from the fact that we managed to turn up on time to the game, but we might as well have not bothered. I think that's as bad as it gets.
"Is all the talk of Wembley on Sunday a distraction? I don't see how that can be the case, apart from maybe one or two that might think they'll be playing anyway because there's no-one else. Well no-one has put their case forward there to play at Wembley, but we've got to pick a team to put out there.
"We spoke about getting three points tonight and keeping the pressure on those above us but at the minute we'll be very lucky to get in the play-offs."