Ash Wilson smashed a last-gasp winner as Spalding Town saw off the title favourites.
It appeared they would pay the penalty for Jamie Cartlidge’s spot-kick being saved.
But his strike partner showed tenacity to wriggle his way through Wisbech St Mary Saints’ defence and force the ball past goalkeeper Callum Summers in a dramatic finish.
Although they left it late, Spalding eventually got what they deserved.
Tom Coote slid home the opener after Cartlidge had created the chance.
Cartlidge – in his first game for 15 months following injury – should have doubled the advantage as he nicked the ball off Chris McAree, only for Summers to push away the shot.
Aaron McKenna sent a lob fractionally wide but he made no mistake with a low finish for the equaliser.
Spalding could consider themselves unfortunate to be level – although Coote had to be in the right place at the right time before the break for a goalline clearance from Alfa Jalo.
Cartlidge was hauled down for a penalty just before the hour mark – but Summers pushed the spot-kick over the bar.
With a hard-fought draw looking likely, up stepped Wilson to win it.
4-4-2: Taylor 7; Deykin 7, West 7, Dickinson 7, Wright 7; Haw 7, Coote 7, Childs 7, Rose 7; Cartlidge 7 (sub Kingman 69 mins, 6), Wilson 8. Subs not used: Newton, Allen, G Smith, Robinson.
WISBECH ST MARY SAINTS
3-1-4-2: Summers; Beckett, Morgan, Brown; McAree (sub Green 32 mins); Watson, Key (sub Lindsay 25 mins), Knight, Jalo (sub Symonds 88 mins); Cawthorn (sub Ryan 61 mins), McKenna (sub Key 73 mins). Sub not used: Hall.
Coote (17 mins, 1-0); McKenna (39 mins, 1-1); Wilson (90 mins, 2-1).
Key, Green (fouls).
Ash Wilson – terrific work-rate all afternoon and got his reward in the final minute.