Socceroos midfielder Riley McGree has ruined Tony Mowbray's return to Middlesbrough, as the new Sunderland boss suffered a derby defeat in his second game in charge.
The South Australian's first-half strike secured a 1-0 Championship win for Chris Wilder's men - just their second of the season - at the Riverside Stadium.
"Crucial win, clean sheet and to do it in the manner we did fighting towards the end on the back foot a little bit it was good, it was sweet," McGree told the club's website.
"Important game to win and hopefully it give us some momentum going forward into the next few games before the international break."
Mowbray, returning to the club for which he made more than 400 appearances as a player before a three-year stint as manager, saw Boro set about their task with relish and after Alex Pritchard had wasted a good opportunity to give the visitors the lead, they started to make their presence felt with wing-backs Isaiah Jones and Ryan Giles prominent.
Black Cats goalkeeper Anthony Patterson had to claw away Jonny Howson's 23rd-minute free kick at his near post and when Giles fed the loose ball back across goal, McGree stabbed a shot into the ground and over the bar.
However, the same combination did the trick within two minutes when McGree controlled Giles' driven cross with his first touch and then dispatched it past Patterson with his second to give the Teessiders a deserved lead.
"It's great to add goals to my game and hopefully contribute more towards the team and towards climbing up the table where we belong," 23-year-old McGree said.
McGree, who scored three times whilst on loan to Birmingham City in the two seasons prior, might have doubled his tally three minutes before the break, but shot tamely at Patterson, although the Teessiders were deservedly ahead at the break.
The Black Cats might have fallen further behind had Patterson not managed to claw away Rodrigo Muniz's 62nd-minute downward header seconds after Matt Crooks had fired across the face of goal, and the keeper denied former Sunderland forward Duncan Watmore, on as a substitute, 10 minutes later.
Boro keeper Liam Roberts had to be alert to keep out substitute Elliot Embleton's late free kick, but Patterson thwarted Watmore once again as time ran down.