Swansea City suffered defeat at the Riverside Stadium as a pair of first-half goals gave Middlesbrough the three points.
Riley McGree and Matt Crooks were on the scoresheet for the hosts as they picked up their first win of the season.
Swansea had promising positions they failed to make the most of but got one back through a Joel Piroe penalty and spent the final stages pressing desperately for an equaliser that would not come.
The Swans also finished the game a man down following a late red card to Ben Cabango and will rue the fact they have lost a game in which they limited Boro to just three shots on target.
The visitors had shown two changes from defeat to Luton. Kyle Naughton and Cameron Congreve coming in for Harry Darling and Matty Sorinola as the latter pair dropped to the bench.
The Swans had started the contest by establishing a degree of control in possession, with Nathan Wood showing some good touches against his former club.
They had the first opening when Michael Obafemi seized on a loose ball and drove to the right. He had Congreve up in support but opted to shoot himself and his weak effort was easily held by Liam Roberts in the Middlesbrough goal.
But Boro made the absolute most of their first opportunity by taking the lead. Congreve’s pass was picked off by Crooks in midfield and he drove forward to feed McGree, who steered the ball into the bottom corner.
The Swans found it difficult to re-establish that initial control they had enjoyed, and it took some excellent defending from Cabango to cut out a couple of dangerous situations.
Cabango then showed his class in possession as a superb pass cut through a number of players in red shirts to find Congreve in space just by the edge of the area, but his first touch allowed Matt Clarke to nip in and steal the ball.
And that missed opportunity was compounded when the home side went straight up the other end to double their lead. Clarke worked Ryan Giles into space on the left, and his cross was turned into the net by a stretching Crooks.
Cabango was soon preventing Isaiah Jones from breaking into the Swansea area and, while Olivier Ntcham and Joel Piroe had efforts on goal in the final stages of the half, the sides returned to the dressing rooms with the home team in control.
Having sent on Sorinola for Congreve earlier in the contest, the Swans boss made another change at the break as Ollie Cooper came on for Ntcham.
Cooper immediately made an impression, linking well on the left and then winning possession to deliver into the box.
Sorinola overhit a delivery from the other side before Swansea spurned a real chance to pull one back.
Cabango again produced a sensational pass to find Ryan Manning free on the left.
The Irishman's cross was a good one, but Obafemi opted to make a run to the near post, when a straight run towards the middle of the goal would have given him a real chance of a tap in.
Boro spurned a chance to put the game out of reach when substitute Rodrigo Muniz met a Crooks cross powerfully, but saw his effort strike the post.
The Swans kept searching for a goal that could get them back in it but when Manning delivered an inviting ball into the box, Piroe could not get a clean contact on it as he tried to get above his marker.
Keeper Roberts then readjusted to save Manning's looping header from a Wood cross before the Swans got a lifeline with 12 minutes to go.
Darragh Lenihan was adjudged to have handled a Cabango header from a corner - moments after Cooper had gone close - and Piroe made no mistake from the spot.
Suddenly it was all Swansea. Sorinola had a cross blocked and Clarke made an excellent defensive header as Liam Cullen waited to meet a Piroe cross.
But the Swans hopes of salvaging a point were dealt a blow when Cabango was sent off for a push on Jones as he looked to waste time before the home side took a free-kick.
However, Swansea continued to press deep into eight minutes of stoppage time, but it was not to be.
Middlesbrough: Liam Roberts, Isaiah Jones, Ryan Giles (Dael Fry 90), Alex Mowatt, Matt Clarke, Riley McGree (Marc Bola 82), Jonny Howson (captain), Paddy McNair, Duncan Watmore (Rodrigo Muniz 57), Matt Crooks (Tommy Smith 81), Darragh Lenihan.
Unused Substitutes: Luke Daniels, Anfernee Dijksteel, Marcus Forss.
Swansea City: Andy Fisher; Kyle Naughton, Nathan Wood, Ben Cabango, Ryan Manning; Joe Allen (Liam Cullen 62), Matt Grimes (captain); Cameron Congreve (Matty Sorinola 31), Joel Piroe, Olivier Ntcham (Ollie Cooper 46); Michael Obafemi.
Unused Substitutes: Steven Benda, Jay Fulton, Harry Darling, Josh Thomas.
Referee: Robert Madley