Swansea City fell to defeat at Elland Road despite Jamie Paterson finding the net inside the opening minute for the visitors.
The midfielder had lobbed Illan Meslier to open the scoring with just 59 seconds on the clock in west Yorkshire as the Swans took a 1-0 lead.
Leeds United would respond in short order through Joel Piroe in a frantic start to the contest.
But the Swans gave as good as they got during the opening period against a home squad stacked with players who were plying their trade in the Premier League last term, and could consider themselves unfortunate to trail at the interval after Georginio Rutter scored right on half-time.
However, Dan James extended the home side’s lead with Michael Duff’s Swans unable to find a way back into the game despite some promising moments.
The Swans had shown one change from the weekend draw with Hull as Josh Key came in for Harrison Ashby, while new signing Yannick Bolasie was among the substitutes.
The hosts, meanwhile, had three former Swans in their starting line-up in the form of Joe Rodon, James and Piroe.
The hosts thought they had opened the scoring with in just 40 seconds, James turning in at the far post only for the offside flag to cut short the celebrations.
But Swansea’s own celebrations started just 19 seconds later as Key’s clipped cross was headed back towards his own goal by Pascal Struijk and Paterson swooped to calmly lob the ball over Illan Meslier and into the net for his second goal in as many games.
However, the lead lasted less than three minutes as Piroe was slipped in on goal by Crysencio Summerville and he steered the ball into the far corner.
It was helter skelter stuff, and Ollie Cooper and Paterson combined to nearly tee up Jamal Lowe just a few moments later.
Carl Rushworth made his first save of the night 10 minutes in, blocked away a Summerville effort at his near post.
The game began to settle down a little with the Swans having bright moments in transition through Paterson, Lowe and Cooper, while also proving calm in possession.
Rushworth held a speculative effort from James on the half-hour mark before Key curled an effort over the bar after more good build-up work from Swansea.
Lowe then nearly sent in Jerry Yates after excellent work by Cooper and Paterson in the lead up, before Summerville had an effort blocked by Ben Cabango and away for a corner.
Key then covered superbly to prevent Glen Kamara steaming in on goal from a Rutter pass.
That looked to have ensured the teams would go in level but instead a long ball from Ethan Amladu found Rutter’s run from out to in, and he controlled to place the ball beyond Rushworth.
It was harsh on the Swans but they started the second half with an excellent move that saw Cabango and Fulton link for the defender to meander forward and feed Lowe, but the forward’s final cross was cut out.
Summerville then wastefully fired over after the hosts had pinched possession high up the pitch but the visitors continued to ask questions; Sam Byram blocking Key’s shot after Lowe had drifted infield and found the full-back in space.
Swansea had a let off when James swooped on a loose pass and Rushworth was equal to the Wales international’s low effort.
But James made no mistake a couple of minutes later when a crunching tackle in midfield secured possession for the hosts and Rutter found the winger’s run for him to fire high into the net.
Duff made a triple change as Harry Darling, Charlie Patino and Liam Cullen replaced Key, Fulton and Cooper respectively.
Leeds sent on Patrick Bamford and Wilfried Gnonto at the same time, and it took alert defending from Matt Grimes to deny the forward a chance at the near post.
Bamford then steered a Summerville pass just wide of the upright, and then stung Rushworth's palms from the edge of the box.
Liam Walsh and Bolasie entered the fray, the latter for his debut and a nice touch from the latter started a move that should have ended with the former getting away a shot, but the chance was passed up.
Cullen then cleared a Rodon flick away for a corner as it looked destined for the top corner as it ended in defeat for the visitors.
Swansea City: Carl Rushworth, Josh Key (Harry Darling 70), Jay Fulton (Charlie Patino 71), Ben Cabango, Matt Grimes (captain), Jerry Yates (Yannick Bolasie 78), Jamal Lowe, Jamie Paterson (Liam Walsh 78), Josh Tymon, Ollie Cooper (Liam Cullen 71), Bashir Humphreys.
Unused Substitutes: Andy Fisher, Nathan Tjoe-A-On, Kyle Naughton, Cameron Congreve.
Leeds United: Illan Meslier, Ethan Ampadu, Joel Piroe, Glen Kamara, Crysencio Summerville (Jaidon Anthony 80), Joe Rodon, Dan James (Wilfried Gnonto 7), Pascal Struijk (captain) (Liam Cooper 89), Archie Gray, Georginio Rutter (Patrick Bamford 70), Sam Byram (Junior Firpo 80).
Unused Substitutes: Karl Darlow, Ian Poveda, Djed Spence, Ilia Gruev.
Referee: Sam Allison
Attendance: 34,905 (485 away)