The Reds went into the game protecting a long unbeaten run but were still unfancied to get a result against Aitor Karanka’s promotion favourites.
But, turning in the kind of away performance that is fast becoming their trademark, Dougie Freedman’s side limited Middlesbrough’s chances and then scored the game’s crucial first goal as Jamie Ward continued where he left off against Bolton Wanderers last weekend.
Nearly 25,000 roared the home side on for an equaliser but the visitors, marshalled as ever by Dorus de Vries and Matt Mills, held firm for a victory that truly confirms their status as a team on the up and sets up Tuesday night's game against Queens Park Rangers at the City Ground.
Speaking afterwards, Freedman said: "That was our toughest match of the season because they grind you down and never stop going.
"We stopped Middlesbrough in the right areas. They were not getting shots from the edge of the box or playing one-twos in front of the area.
"Give us credit for not letting them get time and space. We believed from the first 10 or 15 minutes that we could win this."