Eliezer Mayenda's first-half strike helped Sunderland move to within two points of the Sky Bet Championship automatic promotion places after they earned a 1-0 victory over Derby.
Sunderland came in to the game winless in their last three on the road and seemed keen to break that mini run with a first half they totally dominated, and they rubber-stamped their superiority through Mayenda's fourth goal of the season.
Derby turned up the heat in the second period as they aimed to avoid a fifth successive league defeat and the visitors withstood a barrage of second-half pressure with goalkeeper Anthony Patterson proving to be the hero on three occasions.
Wilson Isidor's recent bad luck continued, after he missed two penalties in their goalless draw to Burnley, the striker then saw a second-half strike ruled out through a belated whistle but Sunderland hung on.
It took nine minutes for the visitors to hit their stride - Isidor's confidence did not seem to have been affected from last weekend's spot-kicks misses and he let rip with a swirling effort from 25 yards that Jacob Widell Zetterstrom had to be equal to.
Derby seemed keen to invite the pressure and they paid the price in the 28th minute.
Jobe Bellingham's darting run through the middle had the home side backtracking, and he played a perfectly timed through ball to Mayenda who expertly slotted home.
New signing Enzo Le Fee, making his second appearance for the club, he hit a free-kick which was destined for the top corner, but Zetterstrom's dive kept the deficit at one.
It took 43 minutes for the hosts to deliver their first shot on target - Callum Elder's corner picked out the head of Ebou Adams which brought Patterson into action for the first time.
The Black Cats came so close to doubling their advantage through a ferocious counter attack - Isidor intercepted a poor Derby corner routine and ran the full length of the field, but pulled the trigger too late which allowed Kenzo Goudmijn to heroically block his effort behind.
The Rams began to sense blood as the noise inside Pride Park lifted. Corey Blackett-Taylor twice provided a cross to fellow substitute Lars-Jorgen Salvesen, but he saw both of his headers stopped by Patterson.
All the momentum was with Derby, who were enjoying their best spell of the game, and had a flurry of corners as they went in search of a leveller, this time Dajaune Brown was unable to guide his header on target from a set-piece.
Sunderland thought they doubled their advantage, but the goal was ruled out through a moment of controversy.
Le Fee latched on to Bellingham's long ball upfield and his initial effort was blocked before falling to Isidor, who smashed in off the crossbar.
Referee Sam Allison then blew his whistle around a minute later, after Isidor had celebrated with boss Regis Le Bris on the touchline, to disallow the goal after a conversation with one of the assistant referees before Sunderland held on for the three points.
After full-time, Allison appeared to gesture to the French striker that the goal was disallowed due to a collison with Adams as both players ran into the Derby penalty area before the ball fell to Isidor to fire home.
The managers
Derby's Paul Warne:
"I do believe in this team and do believe they can go toe-to-toe with all the best teams, but you can't play for just 40 or 60 minutes of a game.
"Sunderland are used to winning. We looked dangerous and it really pleased me, there's ways to lose football matches and our second-half performance I couldn't have asked for much more."
On the disallowed goal: "The thing I thought was strange was the time from it going in to being disallowed, I thought it was lengthy.
"No time during that did I think it was going to be disallowed. I've never seen it before, I don't know why it was disallowed and am grateful for a bit of luck."
Sunderland's Regis Le Bris:
"It's so difficult to judge [the disallowed goal]. It's a little bit strange. I didn't speak with the referees at the end of the game, I just watched a clip back - it's difficult to judge.
"I don't want to say whether it was a good or bad decision because it's a decision you have to make in real time, but I don't know why. It's strange.
"We would like to have a more relaxed end of the game and then it was difficult to the end. It's good because the character of the team is more and more powerful, and you need these experiences to learn to stay connected and work until the end.
"It's a big win, important win for our journey I think. It was a tough game, we had the opportunity to score a second goal, we didn't. It was difficult to press and apply pressure on their first ball.
"It's a good win because they are really efficient in their way of playing and isn't easy to solve."
