Ilkeston were knocked out of the Derbyshire Senior Cup at the first hurdle on Tuesday night as New Mills pulled off a surprise 2-1 win at the New Manor Ground.
The Robins were disappointing but the visitors, from two levels below, deserved their success after a textbook away display.
Elliott Cooke forced an early save out of Robins keeper Richard Stainsby as New Mills began well, Ilkeston's first effort of note only arriving in the 18th minute as Reco Fyfe's low 25-yarder struck the outside of the post and went wide.
Cooke was just wide moments later from distance, the visitors looking useful in attacking positions, Darrhyl Mason then firing low at Stainsby who parried behind for a corner.
Mason Lee's wayward shot threatened at the other end when in a good position, Jamie Walker's long range strike then deflected too high as half-time arrived with the Robins struggling to get a foothold on the game.
New Mills then got themselves in front early in the second-half, as Cooke was fouled just outside the penalty area and Darren McKnight arrowed a low strike into the corner of the net via the hand of Stainsby who could perhaps have done better.
Ilkeston were then denied by a world class save from Dylan Forth as he somehow tipped away Tom Marshall's header from a corner two minutes later, Walker's flicked header inches wide on the hour as Ilkeston responded well.
Walker's next header was then cleared off the line by Benito Lowe with Forth beaten, before the Millers, dangerous on the counter, saw Will Ozono hit the side netting and then Mason force Stainsby into a save low down.
But the Millers would nick their second as the game entered stoppage time, Nathan Webb cutting in from the left and firing low past Stainsby.
The Robins did finally register in the dying moments as Alex Marshall tapped in on the line after a header from a corner had hit the bar, but New Mills held on to secure a well-deserved win and cap a disappointing night for the home side.
Ilkeston: Stainsby, Walker, Campbell-Gordon, Smith (Hollis 75), Freeman, Fenton, Lee (Harrad 53), T Marshall, McDonald (A Marshall 63), Fyfe, Orlando-Young
Subs not used: Durrant, Robertson
New Mills: Forth, Thian, Fallon (Cooper 75), Norris, Lowe, Elliott, Webb, McKnight, Mason, Ozono (Norton 88), Cooke (Riley 78)
Subs not used: Watson
Ref: David Constable