Stoppage-time goals from Andy Bell and Stuart Vasey ensured Bamber Bridge took the spoils after a grandstand finish at Irongate.
The two substitutes finally earned the breakthrough for the home side, who had toiled and toiled to no avail against a resolute New Mills backline.
And, after 75 minutes of stalemate, a wonder strike from the Millers left-back Daniel Caldecott looked to have secured a vital three points for the First Division North strugglers.
Brig, who had recorded five wins on the bounce, were the more ambitious side in a frustrating first half, which saw them fail to really test the Millers goalkeeper Aaron Ashley.
Simon Wiles and Ally Waddecar both spurned chances, and Kieran Pickup dragged a shot wide of goal.
The home side were given a wake up call as New Mills struck the post and four minutes later Caldecott silenced the crowd with a left footed strike into the bottom right corner.
The left-back nearly doubled the visitors’ lead but as the board signalled four minutes of added time, sub Bell pounced on Wiles’ floated cross, diverting the ball home.
A point looked to have been secured, but Brig weren’t done yet, and, with one last push, they sensationally won with the final kick of the match.
Bell’s shot was too hot to handle and with bodies flying everywhere, up popped Vasey to bundle home.
Bamber Bridge: Campbell, Bowyer, Steel, Lawlor, Doughty, Waddecar, Wiles, Kay (c), Marlow,(Parish) Pickup(Bell), Green (Vasey).