Richard Wood grabbed the winner for Rotherham United to close the gap to five points on League One leaders Shrewsbury Town.
The Millers stretched their unbeaten run to 13 matches as they toppled the League One leaders at New Meadow.
Wood’s first-half goal gave the Millers a sixth successive victory and one they fully deserved.
“It was a difficult game,” Warne admitted. “It was a hard game and the pitch wasn’t amazing and was not good for football for either team.
“It became a game of corners, throw-ins and hard work really and I thought on chances created we edged the game.
“We started really well and in the first 15 minutes we were really good but Shrewsbury, top of the league, came back at us but we weathered their storm. In the second half, we really pressed for the second goal, which would have made my life at the side of the pitch much easier but to win one-nil is obviously very pleasing.”
More than 1,000 away fans celebrated wildly at the end as Paul Warne’s promotion-chasing side moved to within four points of the top two.
They were clearly the better side and are now just four points away from the automatic-promotion places.
Wood scored just a minute before the break, poking the ball home after Michael Ihiekwe had got his head on an Anthony Forde cross.
Rotherham were good value for their interval lead and were rarely troubled seriously in the second half as they recorded a famous triumph.
Shrewsbury (4-1-4-1): Henderson; Bolton, Nsiala, Sadler, Beckles; Godfrey; Whalley, Nolan (Payne 68), Ogogo, Thomas (Rodman 84); C Morris (John-Lewis 75). Subs not used: MacGillivray, Lowe, B Morris, Hendrie.
Rotherham (4-4-2): Rodak; Emmanuel, Ajayi, Wood, Ihiekwe; Forde (Williams 63), Towell, Vaulks, Newell (Palmer 90+2); Ball (Lavery 75), Smith: Subs not used: Price, Cummings, Taylor, Yates.