Play-off hopefuls Dereham Town suffered an agonising late defeat as Canvey Island found a winner with just five minutes remaining.
Adam Gusterson's men battled hard in what was a tight game on Saturday, but fell to a Matthew Price strike in the 86th minute to lose 1-0.
The loss leaves the Magpies in seventh place, two points and two places outside the play-offs in the Isthmian League North.
In front of a big crowd at Aldiss Park, the away side - who are pushing for automatic promotion - started brightly and forced three early corners to test Dereham's defence.
Much of the first period passed by without major incident or clear-cut chances, although Toby Hilliard went close in the 25th when his effort at the near post was blocked after good play from Dion Frary to get the byline.
Home keeper Antoni Bort raced off his line to save at the feet of forward Evans Kouassi, before a low drive from Hilliard forced a fine low save from Canvey stopper Bobby Mason.
The teams went in all-square at the break, with Dereham having boasted more of the possession and their defence in outstanding form.
Both sides struggled to find a rhythm at the start of the second half.
On a penetrating run forward, Rhys Logan appeared to be fouled at a crucial stage but nothing was given. At the other end, Kouassi cut in from the left before blazing over the top from the edge of the box.
Despite Dereham beginning to apply some pressure, Bort was forced into a fine save on the hour mark to deny Harrison Chatting’s long-range drive which bounced just in front of him.
The visitors then thought they'd made the breakthrough, but Elliot Ronto's header was flagged for offside.
As play went from end to end, Joe Tarpey lost the ball in his own box with 86 minutes on the clock - enabling Kouassi to square to Price who had the simple task of netting from close range.
It proved to be the decisive moment in a game of few chances.
“It was a tough one to take," said Gusterson.
"There was nothing in the game and it should have been a draw, but one poor mistake at the death has cost us."
The Magpies can quickly put the result behind them on Tuesday evening, when they welcome play-off rivals Brentwood Town.
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