Mark Ward's unbeaten start as AFC boss came to an end as a merciless Cleethorpes ran riot at the Forest Town Arena in this year's Football v Homophobia fixture.
Goals from Craig Disley and Oli Donald gave the visitors a comfortably lead at the break - although it could have been a much bigger margin - before Jon Oglesby secured the three points in the second half.
Craig Disley scored what was virtually the first chance of the game, tucking underneath Jason White after being fed into the middle of the penalty area.
Scott Vernon should have doubled the Owls' advantage when Jack Broadhead's poor header fell in his path with just the 'keeper to beat, but he scuffed his shot well wide.
The Bulls' first chance should have seen them draw level, but Ollie Fearon couldn't steer the ball home from a tight angle despite the close range following Keaton Ward's parried effort.
Cleethorpes deservedly found their second but in peculiar circumstances, as a goalmouth scramble eventually allowed Oli Donald to acrobatically fire into an open net.
AFC were left rattled by the end of the first 45 minutes, with Tim Lowe's deflected effort threatening to finish them off before the break when it bounced off the crossbar.
The Bulls looked to make a bright start in the second half, and were unlucky not to have halved the deficit when Theo Richardson brilliantly denied Charlie Dawes' low effort after cutting inwards from the right.
A sucker-punch blow followed only a minute after, as Julian Lawrence's poor clearance gave room for Jon Oglesby to tap home from close range.
The probability of it not being AFC's day became abundantly clear when Owls 'keeper Richardson denied Fearon from point-blank range on the end of Keaton Ward's inch-perfect ball across goal.
With their tails up, the visitors continued to threaten a fourth goal and should have found it when Donald struck the crossbar from 10 yards out on 82 minutes, with the Bulls unable to produce a response.
Mark Ward's side remain in 14th and five points above safety despite the defeat, and now turn their attention to an important trip to Belper Town.
Final score | AFC Mansfield 0-3 Cleethorpes Town
Scorers | Disley (6'), Donald (32'), Oglesby (48')
AFC Mansfield XI | White, Marsden, Dudley, D'Laryea (C), Lawrence, Broadhead, Dear, Buxton (Fletcher 58'), Fearon, Ward, Dawes (Ghaichem 58')
Unused substitutes | Wall, Crosby
Yellow cards | Fearon (62'), Fletcher (85') Marsden (89')
Red cards | N/A
Cleethorpes Town XI | T. Richardson, Lowe, Topliss, Disley (C) (J. Richardson 67'), Walker (Gray 56'), Donald, Robertson, Flett, Vernon, Collins (North 74'), Oglesby
Unused substitutes | Batty, Mascall
Yellow cards | N/A
Red cards | N/A
Man-of-the-Match | Cameron Dear
Attendance | TBC