Shane Long's second-half header consigned Francesco Guidolin to his first defeat as the Swans' four-match unbeaten run ended at the Liberty with a 1-0 loss to Southampton.
The striker met James Ward-Prowse's pinpoint cross in the 70th minute with his header squirming under Lukasz Fabianski.
It proved a frustrating afternoon for the Swans, who failed to threaten a Southampton defence which hadn't conceded a goal in the previous five matches.
Gylfi Sigurdsson's first-half volley was as good as it got the Swans, who sit 16th with 27 points from 26 games - three points above Norwich City and Newcastle United.
The Swans kept faith with the same starting XI as head coach Francesco Guidolin stuck with the side that was held by Crystal Palace last time out.
The only change saw Ki Sung-Yueng named on the bench following his full recovery from concussion which saw him miss the game against the Eagles.
Southampton went into the game having won four of their last five games while they haden't conceded a goal in that period.
Ronald Koeman was without Victor Wanyama, however, as the midfielder served a five-match ban.
SWANS: Lukasz Fabianski, Angel Rangel (Kyle Naughton, 67), Federico Fernandez, Ashley Williams (capt), Neil Taylor, Leon Britton (Bafe Gomis, 73), Jack Cork, Gylfi Sigurdsson, Andre Ayew, Wayne Routledge (Modou Barrow, 60), Alberto Paloschi.
SUBS: Kristoffer Nordfeldt, Jordi Amat, Ki Sung-Yueng, Leroy Fer.
SOUTHAMPTON: Fraser Forster, Jordy Clasie, Jose Fonte (capt), Shane Long, Steven Davis, Oriol Romeu (Cedric Soares, 63), James Ward-Prowse, Virgil Van Dijk, Graziano Pelle (Charlie Austin, 74), Ryan Bertrand, Matt Targett (Maya Yoshida, 86).
SUBS: Maarten Stekelenburg, Sadio Mane, Dusan Tadic, Juanmi.
In a steady opening 20 minutes to the game, both sides managed to muster early chances.
Neat link-up play from Neil Taylor and Gylfi Sigurdsson sent Wayne Routledge down the left, but his low cross failed to find Alberto Paloschi in the box.
Graziano Pelle then volleyed straight at Lukasz Fabianski following a Shane Long knock down, before the Swans replied via Andre Ayew, who galloped forward before seeing his low shot gathered by Fraser Forster.
Southampton then threatened with dangerous deliveries into the box. First, Jose Fonte met James Ward-Prowse's free-kick but he could only head wide, before another cross found Oriol Romeu, but he was denied by Ashley Williams' last-gasp block in the box.
Another inviting ball into the box, this time by Neil Taylor, curled along the face of goal but no white shirt could make contact.
Gylfi Sigurdsson was the next to try his luck, with the midfielder holding off Jordy Clasie before turning back onto his left foot before firing a half-volley high over the crossbar from 30 yards.
Shane Long and Clasie were then denied in quick succession through some heroic defending by Federico Fernandez and Jack Cork, with the pair sliding in to block efforts.
Then, in the final minutes, the Swans wasted a great chance to take the lead as Paloschi flicked on a cross for Sigurdsson, but he volleyed way over the crossbar from 12 yards out.
Another big opportunity followed - the best of the game so far - as Steven Davis crossed perfectly for Pelle, but he headed straight at Fabianski from ten yards.
HALF-TIME: Swans 0 Southampton 0
Both sides continued to cancel each other out, with a Romeu header dropping wide from Ryan Bertrand's cross the first threat after the break.
Sigurdsson then fired wide after controlling a headed clearance from Angel Rangel's cross, before the visitors had the ball in the net only for it to be ruled out.
After Ward-Prowse's cross was collected by Fabianski, Fonte nudged the ball out of the Polish keeper's hands before Pelle tapped the loose ball into the net. Referee Jonathan Moss, however, awarded the Swans a free-kick.
The Swans made the first change of the game on the hour mark as Modou Barrow replaced Routledge.
Moments later, a Sigurdsson free-kick into the box met Williams, but he got the slightest of connections among a crowded penalty area and it dropped wide.
Another change followed, with Kyle Naughton coming on in place of Rangel with 24 minutes remaining.
But, with 20 minutes to go, the big moment arrived.
Ward-Prowse delivered another inviting cross which found the unmarked Long, and his low header just squirmed under Fabianski.
Francesco Guidolin made his final change as Bafe Gomis came on in place of Britton to give more attacking options.
It failed to give the Swans the injection they were looking for though, although a penalty claim for a shove by sub Maya Yoshida on Paloschi was waved away late on.
But that was the end of the action as the Swans fell to a disappointing home defeat.