Sunderland duo Stephen Elliott and Neill Collins stood tall as the Black Cats kept pace with the Championship's top two with a hard fought, but deserved victory at Pride Park.
The Republic of Ireland international scored one goal and set up the other for Dean Whitehead, while his Scottish colleague provided a solid platform for a win which sent 1,750 travelling fans home happy and dreaming of a return to the Premiership.
There was no need for Mick McCarthy to turn to his maverick goalkeeper Mart Poom, who took his place on the bench, to make a late cameo and rescue things as he did last season as the away win turned out to be quite comfortable overall - although there was nothing between the sides in the opening 45 minutes.
Wins for both Wigan and Ipswich meant the Black Cats did not close the gap on the top two teams after the weekend's results, but they could draw comfort in their win.
It now provides a four point cushion between them and fourth placed Reading, who drew at Burnley on Saturday.
Mick McCarthy's side has enjoyed fluctuating fortunes since Christmas with two wins, two defeats and a draw, but then so have their closest rivals.
At one point the top three championship teams seemed to have been engaged in a nightmarish tussle with the Chuckle Brothers, given the propensity of the top two to pass the Championship lead from one another, and the Black Cats' inability to take advantage.
But with both Ipswich and Wigan rediscovering their pre-festive form, the Sunderland boss will be relieved to see his side get back on track in the East Midlands yesterday.
Injuries to Steve Caldwell and skipper Gary Breen did not help his preparations and he was forced to start with inexperienced pair Neill and Danny Collins at the heart of his defence.
With this in mind the Black Cats' boss brought back Jeff Whitley from suspension to provide cover in front of the back four in place of the impressive Sean Thornton. Julio Arca also returned with Andy Welsh making way.
McCarthy claimed Derby County were the best side to have visited the Stadium of Light this season and it is hard to disagree.
George Burley's well drilled outfit made a mockery of their lowly league position and had Sunderland chasing shadows - certainly in the first half - in the 0-0 draw on Wearside.
Inigo Idiakez was the Black Cats' tormentor in chief on that occasion and had injury not robbed the Rams of his silky skills that day the home side could have been on the wrong end of a costly defeat.
Whitley and Carl Robinson obviously remembered the Spainiad's eye-catching cameo and despite taking every opportunity to suffocate his space, he still managed to find enough air to breathe life into Derby's best attacks in the first half.
But once Sunderland got their noses in front there was only going to be one winner.
Whitley came closest to breaking the deadlock for the visitors when he crashed the ball just over the bar from the edge of the 18-yard box on 16 minutes.
Elliott followed the Northern Ireland star's effort a minute later when his jinking run ended with a curling left footed shot, which just cleared goalkeeper Lee Camp's left hand post.
Derby hit back, however, and Sunderland survived a scare in the 36th minute when a Richard Jackson ball played between goalkeeper Thomas Myhre and his back four had the visitors' defence startled like a rabbit caught in a car's headlights.
Fortunately, referee Phil Crossley gave Neill Collins the benefit of the doubt and didn't give George Burley's side the penalty he felt they deserved when he clattered Grzegorz Rasiak after he appeared on the defender's blind side.
The impressive Scot survived once again three minutes later when he was adjudged to have brought down ex-Black Cats striker Tommy Smith outside the box.
Idiakez crashed the resulting free-kick against Myhre's crossbar much to the visitors' relief. And this was as close as it got for the Rams.
There seemed nothing on when full back Jeff Kenna shepherded Marcus Stewart into the left-hand channel seven minutes into the second half. But the former Ipswich striker managed to squeeze the ball through to Arca, who stung the fingertips of Camp, and left Elliott with the simple task of tapping home from close range for his 12th goal of the season.
Less than 15 minutes later the Republic of Ireland international was the Wearsiders' hero once more when he swapped his shooting boots to turn provider. The little striker initially looked as if he was chasing a lost cause. But with his unswerving enthusiastic determination to chase everything, he kept the ball in play to slide it into the path of the industrious Dean Whitehead to slam home from six yards.
Derby tried to hit back but with Sunderland's back four in majestic form they found no way through and held on to record their first clean sheet in seven games.
Result: Derby County 0 Sunderland 2.
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