Ben Cabango (centre) was made Swansea captain after Matt Grimes left in January
Sunderland were made to wait to guarantee themselves a top-four finish – and a home second leg in the Championship play-offs – as they lost at home to in-form Swansea City.
With the Black Cats already sure of their play-off place and the Swans all but safe in mid-table, there was not a great deal riding on this match.
Both sides had chances in an even first half, with Sunderland's Wilson Isidor having a goal disallowed for offside.
Ben Cabango blasted Swansea in front after the break as he followed up from centre-back partner Harry Darling's header which hit the crossbar.
Sunderland's efforts to score a late equaliser were in vain as they stay fourth in the Championship table, 12 points ahead of fifth-place Bristol City with four games left in the regular season.
Swansea's third successive win lifts them up to 12th position, now closer to the top six than they are the relegation zone.
Having already secured a play-off place with a goalless draw at Norwich City on Tuesday, Sunderland may already have half an eye on the post-season fixtures, but they came into this game wanting victory to secure a top-four finish and home advantage in the second leg of the play-offs.
Swansea, meanwhile, looked to be certain of playing in the Championship next season following back-to-back wins under interim boss Alan Sheehan.
There was not much between the teams in a goalless first half with Swans midfielder Lewis O'Brien having a few early efforts on goal either side of Isidor's disallowed goal for the home side.
The best chance before the break fell to the hosts' Tommy Watson, whose low shot was kept out by the feet of Swansea keeper Lawrence Vigouroux.
The Swans took the lead in the 58th minute as Darling headed Eom Ji-sung's free-kick against the bar and Cabango rifled the rebound into the roof of the net.
Sunderland had chances to level with the likes of Eliezer Mayenda and Trai Hume going close, while the Black Cats also had a late penalty appeal rejected.
But Swansea, who were just six points away from the bottom three last month, held firm to continue their impressive resurgence under Sheehan.
Post-match reaction
Sunderland head coach Regis Le Bris:
"This was a disappointing result. We expected more and wanted to win but it wasn't to be today.
"We didn't create many chances and it was difficult to put them under pressure.
"They were well-organised and it wasn't easy to find a solution. At the same time, we didn't find the good dynamic, the rhythm to find a solution."
Swansea City interim boss Alan Sheehan:
"We came out of the blocks really well and we knew we had to. A third game in a week, it's really difficult.
"I think we were excellent and should have been one or two up. They took a bit of control of possession more than creating big chances.
"Second half it was nip and tuck up to about 65 or 70 minutes and then we looked like we had to find a way to dig in and defend the box, and we did that really well, so a bit of everything."
