Four first-half goals settled the outcome as Swansea City fell to defeat against Southampton at the Swansea.com Stadium.
A Saints side seeking to break a club record for games without defeat surged into an early lead thanks to goals from Che Adams and Will Smallbone, although the second of those should not have stood as a clear offside was missed in the build-up.
Jamie Paterson’s sixth goal of the season got one back for the Swans, but Flynn Downes fired home just a couple of minutes later to make it 3-1 at the interval.
Neither side was able to add to their tally during the second period, but that did not tell the story of a closing 20 minutes Swansea will look back on with a sense of what could have been, as they created and spurned a series of chances to get something from the game.
Charlie Patino, Jerry Yates and Paterson were all unable to convert, with the latter pair hitting the woodwork, while Joe Allen and Yannick Bolasie were also denied.
The final result was a disappointing one for head coach Luke Williams on his home league bow as Swans boss, but he will take positives from the way his side nearly battled their way back into the contest against a Southampton side stacked with players with Premier League experience and firmly in the hunt for a return to the top-flight.
Williams had made just one change from the draw at Birmingham with Harrison Ashby coming in for the injured Sam Parker, while Liam Cullen made his 100th appearance for his boyhood club.
The Saints had an early sight of goal when Adams flashed a volley wide of the target as the visitors enjoyed plenty of ball early on.
But Adams made no mistake in the sixth minute when he tapped home at the far post after Carl Rushworth had parried Stuart Armstrong’s initial shot.
Rushworth then held a low effort from Adam Armstrong, before pulling off a tremendous double stop as he saved Adams’ initial effort and smother an Armstrong follow-up.
Swansea looked as if they had started to settle, with Cullen and Josh Tymon having some joy down the left flank, while Taylor Harwood-Bellis went in the book for hauling Paterson down as the midfielder lofted the ball over the Southampton defender.
However, Saints doubled their lead in fortuitous circumstances when Stuart Armstrong was allowed to deliver despite clearly being offside by a considerable distance, and Smallbone tapped in from close range.
It took a good block from Tymon to deny Adam Armstrong as he raced on to namesake Stuart’s pull-back, before Tymon steered an outside-of-the-foot strike over the bar from a Paterson cutback and Cullen lay-off.
Rushworth did well to hold a rising Stuart Armstrong drive just before the half-hour mark, with the hosts then lifting the pressure to pull one back.
Ashby broke away into space down the right and his terrific delivery nearly picked out Jamal Lowe.
The ball fell for Cullen, who lofted it back into the box for Paterson to head home from six yards.
However, Saints swept straight up the other end for Downes to fire into the bottom corner via the aid of a deflection off Lowe and make it 3-1 at the break.
Swansea nearly responded with a goal of their own seconds into the second half, Paterson curling wide after Tymon had played him into space on the left side of the area.
Lowe then won possession and sent a ball into the box that Jan Bednarek managed to clear.
But Southampton regained their composure and it took more astute defending by Tymon to clear a Ryan Manning cross from Stuart Armstrong’s purposeful surge down the left.
The Swans made a triple change with 25 minutes to play as Yates, Bolasie and Patino came on for Lowe, Ashby and Cullen respectively.
And the hosts missed a big chance to set up an exciting finale when they worked Tymon into the area and he unselfishly picked out Patino, but the substitute’s final effort was well wide of the mark.
Yates was then unable to convert when Paterson’s cross found him unmarked at the far post, with the ball hitting the woodwork as he attempted to turn it in.
Paterson was next to be denied by the woodwork, Gavin Bazunu turning his effort onto the post, before Allen had an effort blocked and Bolasie's header was parried wide as it ended in defeat for the Swans.
Swansea City: Carl Rushworth, Jay Fulton (Joe Allen 75), Harry Darling, Matt Grimes (captain), Jamal Lowe (Jerry Yates 65), Jamie Paterson, Josh Tymon, Liam Cullen (Charlie Patino 65), Nathan Wood, Harrison Ashby (Yannick Bolasie 65), Bashir Humphreys.
Unused Substitutes: Andy Fisher, Kristian Pedersen, Nathanael Ogbeta, Kyle Naughton, Ollie Cooper.
Southampton: Gavin Bazunu, Kyle Walker-Peters, Ryan Manning, Flynn Downes, Adam Armstrong (captain), Che Adams (Sekou Mara 75), Will Smallbone (Shea Charles 87), Stuart Armstrong (Joe Rothwell 75), Taylor Harwood-Bellis (Jack Stephens 59), Ryan Fraser, Jan Bednarek.
Unused Substitutes: Joe Lumley, Mason Holgate, Carlos Alcaraz, Sam Amo-Ameyaw, Tyler Dibling.
Referee: Matthew Donohue
Attendance: 17,356
