Sheffield United jumped to third place in First Division with late goals from substitute Wayne Allison and Michael Tonge leaving Grimsby Town rock bottom.
Striker Paul Robinson, on loan from Wimbledon, shocked United with a ninth minute strike before the Sheffield side produced a late smash and grab raid.
Grimsby threw away two chances in the space of a minute, Robinson failing to connect six yards out as Steve Kabba stabbed in a low cross.
Centre-back Steve Chettle followed up pulling his header high over the bar before Robinson broke the deadlock.
United gave Stuart Cambell too much space and his low cross from the left was drilled past Paddy Kenny by the unmarked Robinson.
Danny Coyne foiled the lively Carl Asaba producing a one-handed block to push away his stinging drive as the Sheffield side probed for a gap in the Grimsby back four. But lowly Grimsby had the Sheffield side in trouble again, Kabba weaving past Shaun Murphy.
Little Canadian striker Paul Peschisolido wasted an opportunity after 36 minutes snapping a tame header straight at Danny Coyne after neat work from Asaba.
The ex-Gillingham man was stopped again by the Grimsby keeper two minutes later as Asaba beat his marker to connect with a Stuart McCall free-kick, Coyne producing another one-handed save to keep United at bay.
Allison levelled matters with an 81st minute header from a Tonge corner before Tonge fired in a right-foot shot from just inside the area two minutes from time to grab the victory