Marcus Tavernier's first league goal sent Middlesbrough into the Championship's top five and left crisis club Sunderland rooted to the foot of the table following this 1-0 derby defeat.
The 18-year-old's sixth-minute finish settled a Tees-Wear clash short on genuine quality which extended the managerless Black Cats' run without a league win to 14 games.
Sunderland, with caretaker managers Billy McKinlay and Robbie Stockdale looking on, should have been ahead by the time Tavernier struck with Lewis Grabban failing to add to his tally of five goals in his last three games from close range.
But they eventually wilted and it was Boro who looked more likely to add to their tally as time ran down in front of a crowd of 29,277 at the Riverside Stadium.
Grabban's big moment arrived with the game just three minutes old when Boro keeper Darren Randolph, who was hampered by the sun throughout the first half, spilled Didier Ndong's well-struck shot, but somehow managed to block the striker's follow-up from point-blank range.
The Sunderland frontman was still bemoaning his misfortune when the visitors fell behind three minutes later, teenager Tavernier turning home Martin Braithwaite's pull-back at the near post after Stewart Downing had unpicked the Black Cats' defence.
In fairness, the visitors gave as good as they got as they looked for a way back into the game with Lee Cattermole also testing Randolph from distance and Aiden McGeady going to work on Republic of Ireland team-mate Cyrus Christie.
McGeady sent a dipping shot just over six minutes before the break after tricking his way past Grant Leadbitter, but the home side went in at the break with their lead intact.
Sunderland picked up where they had left off after the restart and Grabban might have done better when he headed harmlessly over from Bryan Oviedo's 52nd-minute cross.
But it took a fine save by Ruiter to deny Braithwaite four minutes later after Christie had combined with striker Britt Assombalonga to set him up.
With Braithwaite and the marauding Christie prominent, Boro began to dominate, although without testing Ruiter unduly until Downing curled a low 76th-minute free-kick around the wall and saw the keeper make a solid save.
McGeady might have snatched a point nine minutes from time after running on to Oviedo's square ball, but he sent his shot wastefully wide to the amusement of the home fans behind Randolph's goal.