The visitors were on a fine run of form going into the game and were looking to make it three consecutive wins at the Liberty Stadium.
Read how it all unfolded in our live minute-by-minute commentary below.
2.05pmGood afternoon! Thanks for joining me today on Sports Mole for what is sure to be an entertaining game of football. Both sides have played some excellent stuff already this season and I'm pretty certain there will be goals for either side at the Liberty Stadium.
2.07pmFirst off, it's time for the team news.
2.08pmSwansea City starting XI: Fabianski, Rangel, Fernandez, Williams, Taylor, Ki, Shelvey, Sigurdsson, Dyer, Routledge, Bony
2.08pmSwansea City substitutes: Tremmel, Richards, Bartley, Carroll, Emnes, Montero, Gomis
2.09pmSouthampton starting XI: Forster, Clyne, Yoshida, Fonte, Bertrand, Schneiderlin, Cork, Ward-Prowse, Tadic, Long, Pelle
2.09pmSouthampton substitutes: K. Davis, Gardos, S. Davis, Wanyama, Mayuka, Targett, McQueen
2.11pmTwo changes for Garry Monk's side then, as Federico Fernandez makes his full Premier League debut in defence as he replaces the injured Jordi Amat. Meanwhile, last season's top goalscorer Wilfried Bony has been restored to the attack after being dropped for last week's visit to Chelsea. Bafetimbi Gomis is relegated back to the bench.
2.15pmThere are also two changes made by Ronald Koeman despite a 4-0 win at Newcastle last time around. Steven Davis is back on the bench and has been replaced by James Ward-Prowse in midfield. Further back, Maya Yoshida comes in for Toby Alderweireld, who misses out altogether.
2.19pmIt'll be interesting to see how Swansea bounce back after last weekend's defeat. Nobody was expecting them to get anything against a rampant Chelsea side, but having made such a positive start to the season, the 4-2 loss may have knocked some of the stuffing out of Garry Monk's team. Having said that, they have been a joy to watch in their opening four league games and if they can return to similarly scintillating form, they have a great chance of picking up all three points.
2.22pmSouthampton have been another side to surprise everyone in the opening weeks. Yes, they lost their opener at Liverpool, but they deserved at least a point at Anfield. Since then, they're unbeaten in three, but it's their last two games that really stand out - a 3-1 victory at West Ham and an equally outstanding 4-0 win at home to Newcastle. What's more, they've done it without Luke Shaw, Dejan Lovren, Adam Lallana, Rickie Lambert and Calum Chambers! And that's quite a cast!
2.24pmConfirmation from Ronald Koeman that Toby Alderweireld has missed today's game with a slight hamstring problem. It doesn't sound as though it'll keep the defender out for too long, though.
2.26pmToby Alderweireld's one of a number of astute signings made this summer by the Saints. The 25-year-old defender won La Liga last year, but he's been tempted to play Premier League football by the club. Graziano Pelle's hit the ground running up top, while Dusan Tadic has been mesmerising so far. Ryan Bertrand was a clever, cheap signing to replace Luke Shaw, too.
2.30pmHere's a whistlestop look at the short journey the Southampton players will be making from the away dressing room to the pitch for kickoff in just under half an hour.
2.35pmDon't forget, Sports Mole will be bringing you all the results from across Europe this afternoon, so feel free to check out some of the many of other live commentaries on the site by heading to our home page and clicking the links. Make sure you come back to this game though, because it's bound to be the most entertaining!
2.40pmThere's already been one Premier League result today, and that saw QPR come from behind twice to rescue a 2-2 draw at home to Stoke City. That could be a very important point for Harry Redknapp's side come the end of the season!
2.42pmBack to the game in Wales though, and I think Wilfried Bony will be a huge player today. If he's on form, the home side will win. He was close to unplayable at times last season, but he hasn't netted a single goal this season so far. I'm pretty sure that Garry Monk dropped him last week as a wake-up call to remind him that his place in the side isn't a certainty. Will he heed the warning?
2.45pmIf last season is anything to go by, then Southampton must be favourites - the south coast club won both league games in 2013/14 and haven't lost any of the last five matches between the two sides.
2.48pmPREDICTION! Time for a prediction from me then! I've put my neck out and said there'll be goals, so I'm going to go with a 2-1 win for the hosts. I also fancy Wilfried Bony to get back among the goals.
2.51pmBelieve it or not, this is a top-four clash! The home side are currently third, with Southampton just one place and two points behind them.
2.57pmThe teams are making their way out on to the pitch, so not long until kickoff now!
2.59pmNathan Dyer's out on the pitch and will start for Swansea City, He's been mightily impressive so far this year, and can count himself unlucky to have missed out on Roy Hodgson's latest England squad.
1 min KICKOFF! We're underway!
4 minSouthampton on top in the early stages, with Cork and Clyne putting in crosses from the right, but they come to nothing. At the other end, Dyer sets off on a run but pushes Bertrand in the back and it's a free kick to Southampton.
5 minA good atmosphere inside the Liberty this afternoon. And why wouldn't it be? Both sets of fans have had plenty to cheer already this season!
7 minSwansea move the ball so quickly in attack. Bony, Shelvey and Ki combine to set up Taylor, who is scampering forward from left-back, but it all becomes a bit too intricate and he ends up losing the ball in the Southampton box.
9 minCork harasses Ki, but is penalised for a foul. The away side are allowing Swansea very little time on the ball.
10 minGood possession by Swansea is wasted as Taylor launches a straight, long ball which runs out of play for a goal kick. Ten minutes gone and no shots on goal yet.
11 minSwansea definitely on the front foot now. They're nipping in front of the Saints players and winning all the 50/50's. They've just got to be a little more assured in possession.
12 minCLOSE! There it is! Swansea work the ball down the left flank and Routledge swings in a cross with his right foot. Bony throws himself at it, but it's just too high. Dyer arrives at the far post, but he makes a mess of the half volley under pressure and Southampton scramble it clear to safety. A very well-worked move!
14 minIt's all Swansea at the moment. Southampton just cannot get a touch on the ball!
15 minSAVE! The first save of the afternoon. It's quite routine in all honesty, but a good chance nonetheless for Swansea, as Sigurdsson collects Bony's flick on and fires towards goal, but it's a tame effort straight at Forster.
16 minPelle is penalised for a high foot as he tries an highly ambitious overhead kick from Clyne's hooked cross and almost claters Fernandez in the face!
17 minThe game's come to life now! Swansea go straight down the other end and have another sight of goal. This time it's Routledge, who slices a 25-yard volley wide of goal.
19 minJames Ward-Prowse is standing over a free kick for Southampton now. It's 35-yard yards out, but the youngster has an outstanding delivery... but it's cleared. Curse of the commentator!
20 minBOOKING: A yellow card for Bony as he smashes into Yoshida as the defender jumps to clear a header. It was a bone-shuddering challenge and the defender must have been winded by that!
21 minBOOKING: A booking for Southampton now, as Fonte enters the book. It looks like a very harsh decision in all honesty. He comes flying in on the slide and nicks the ball off the feet of Bony, but the referee deemed it a dangerous challenge. A bit of bite to the game now!
23 minDear oh dear. Taylor toe-ends a cross straight out of play for a goal kick, with Bony and Shelvey waiting in the box.
24 minGood work from the left-back defensively though, as he scuttles in front of Long and smothers the danger. He was alert a few minutes ago too to shepherd the ball away from Tadic.
25 minSwansea seem to be forcing it a little. Shelvey, standing 40 yards from goal in a central position, tries to stab a lofted ball through to Bony, but it has far too much on it. They've just got to relax a little in those situations, because when they've worked the ball better, they've had sights of goal.
27 minUPDATE: No goals anywhere in the Premier League so far this afternoon. Will the first come here at the Liberty?
28 minCROSSBAR! Nearly! Routledge should have put the home side ahead there! Dyer played the ball into Sigurdsson, who threaded a wonderful through ball into the path of Routledge with his first touch. The winger latched onto the ball and lashed a strike with the outside of his boot that clipped the top of the crossbar before sailing over the bar!
29 minAnother chance for Swansea. Absolutely top drawer play from the the home side sees Ki charge forward from midfield and collect Bony's layoff, but the South Korean's low drive from an angle is blocked superbly by Yoshida.
31 minBOOKING: Bizarre scenes at the Liberty. Dyer is penalised for a late challenge on Long, but Yoshida is the man shown a yellow card by Jon Moss. I can only imagine it's for something the defender said to the referee.
33 minReplays suggest that the Japanese centre-back was shown the yellow card for his reaction to Dyer's foul, as he went towards the referee waving an imaginary card trying to get the winger booked. Imagine if players were shown a yellow card every time they did that - there'd be no-one left on the pitch in La Liga!
35 minSAVE! The first sight of goal for Southampton comes from Pelle, as the big striker forces Fabianski into a low save at his near post with a scuffed half volley. It was a tough chance as he was going away from goal as he connected with Bertrand's cross from the byline. Better from Southampton.
37 minOFF THE LINE! So close! Bony connects with Sigurdsson's corner at the near post and connects with a textbook header, which he glances down towards the far post, but Bertrand sticks to his task well and clears the ball off the line.
38 minOn second viewing, Bony should have scored. It was a completely free header from less than six yards out and it came off his shoulder. If he'd got a proper connection with the header, Swansea would probably be a goal up.
39 minRED CARD! My oh my! That's a game changer! A minute after wasting a glorious opportunity, Bony is shown a second yellow card for a reckless challenge on Yoshida! The ball gets away from the big Ivorian and he flies into the Japanese defender from behind and swings both legs around his opponent. Such a stupid challenge and I've seen straight red cards given for less. Both bookings were idiotic.
42 minThat is likely to change the whole dynamic of the game. Swansea were easily on top until that moment of madness from Bony. The frustration got to the striker, but he's left his side in the lurch here. It looks as though Swansea will try to get to half time before introducing a striker.
43 minSafe hands from Fabianski, who collects Bertrand's high looping cross on the line with Long and Cork lurking for any scraps.
44 minSouthampton win a corner as Taylor nods Bertrand's deep cross behind. The first corner of the afternoon for the visitors.
45 minIt's a disappointing delivery by the usually dependable Ward-Prowse and Swansea clear. Fonte flies in on Routledge with a reckless tackle, but doesn't quite make contact with the winger. Monk is asking the fourth official why the Southampton centre-back hasn't been shown a yellow card for that tackle, as Bony was a minute earlier. He's entitled to ask the question, but it was nowhere near as dangerous as Bony's lunge.
45 minTHREE MINUTES OF ADDED TIME: The home side have three minutes to hold on to the break.
45+2 minSwansea are just keeping the ball until the break. A decent decision.. until they lose the ball and Williams fouls Pelle. A chance for Ward-Prowse to make it 1-0 with a free kick from 25 yards right on the stroke of half time.
45+3 minIt was left for Tadic, who picked out Pelle at the far post, but the striker's layoff found no-one.
3.49pmHALF TIME: Swansea 0-0 Southampton
3.51pmYou can't say it wasn't entertaining! Swansea have been by far the better side, and have hit the bar before seeing a shot cleared off the line. But Bony's dismissal towards the end of the half has changed the whole complexion of the match. I just cannot understand why he flew into the second challenge when he was already on a booking. There was only one outcome, and although the home support booed Jon Moss off the pitch at the break, the referee had no choice other than to send him off.
3.56pmThere's only been one game with goals in the Premier League so far this afternoon, and that's the one at Villa Park, where Arsenal lead Aston Villa 3-0. The Villains had only conceded one league goal all season prior to today! Here's Giuseppe Labellarte's half-time report from the game.
4.00pmWe're likely to see Bafetimbi Gomis come on at the break for Swansea, but who will make way? It could by Sigurdsson, despite the midfielder's impressive start to the year. One thing is for sure, though, Southampton will have much more of the ball in the second period.
4.04pmSUBSTITUTION: The teams are back out on the pitch and Swansea have not made any changes, but Southampton have. Yoshida struggled in the first half, and he's been replaced by Florin Gardos.
46 minKICKOFF: We're back underway.
47 minAn interesting decision by Monk to not bring Gomis on. Sigurdsson is playing as a 'false nine' as far as I can see, but it could be difficult for Swansea to find an outlet if needed, which Bony offered throughout the first half with his incredible strength when holding up the ball.
48 minBOOKING: A free kick for Swansea on the right touchline as Bertrand flattens Dyer. It's not the first time he's stopped the winger illegally, and he's sturggled a little against the pacey 26-year-old.
50 minAlready Southampton are on the front foot. Taylor easily clears Tadic's weak cross, but the tables have turned. It's going to be a long half for Swansea.
52 minSwansea come forward and Ki's cross is headed away by Fonte, but it rebounds back off a teammate. Luckily for him, it runs straight back into the hands of Forster. That could have ended disastrously!
54 minAlready it's clear to see Swansea's attacks are more measured this half. They're happy to just keep hold of the ball rather than racing forward at every opportunity as they look to conserve energy with just ten men.
55 minPelle and Long have found it difficult to link up today and there's just been further proof of that. Pelle nods a long ball back to Long, but he can;t quite get it under control and he attempted pass back to his teammate is cut out.
55 minCLOSE! Tadic cuts in front the left flank onto his right foot and sends a shot towards goal, which takes a slight nick off the foot of Dyer. It loops up over the stranded Fabianski and lands on the roof of the net. The home fans must have had their hearts in their mouths then!
57 minPelle is causing a bit more of a nuisance in this half, but he goes down pathetically after a slight nudge by Williams. He knew he was never going to get a decision, but it's not the first time the giant striker has gone down under the slightest touch.
58 minSAVE! Proof that he can stay on his feet when he needs to! Pelle holds off the challenge of Fernandez and sends a header towards goal from 12 yards which Fabianski collects comfortably on the bounce.
60 minThat substitution has seen Routledge switch to the right wing, with Montero operating on the opposite flank.
61 minThe game has swung entirely now. It's all Southampton at the moment as they continue to come forward in wave after wave of attack. The difference is that Swansea just don't have the option to ping it into Bony, who made it stick in the first half whether it was played to his feet, thighs or chest.
62 minFabianski tips another Pelle header over the bar. In truth, the weak effort was probably dropping onto the roof of the net, but the Polish stopper wasn't to know that and went for the safe option.
63 minSUBSTITUTION: Second change of the afternoon for the Saints, with Steven Davis replacing the busy, but ineffectual Cork.
65 minCHANCE! Another Pelle header goes close. The 29-year-old connects with Clyne's cross from deep and glances it well wide of goal. He's had plenty of chances, but he's failed to make any of them count so far. He has 25 minutes left to net a winner for the visitors.
67 minThe game's been stopped as Ward-Prowse has gone down with a serious looking injury here. It actually came in a challenge that he made on Fernandez which was very nasty. It was very much like the one Bony was sent off for, but the youngster wasn't shown a yellow card and he's very lucky.
69 minSUBSTITUTION: That injury has forced Koeman into his third and final substitution of the afternoon, as Wanyama replaces Ward-Prowse, who leaves the pitch on a stretcher.
70 minTadic tries an incredibly ambitious strike from range the flies harmlessly over the bar. Swansea will be happy with that!
72 minA chance for Tadic to test Fabianski with a 25-yard free kick and he does. It goes through the wall and seems to be heading for the bottom corner, but it doesn't have enough power and the goalkeeper holds on at his near post.
73 minA panicked moment for Williams, who nods Tadic's cross behind for a corner.
74 minSwansea embark on a rare foray forward, but Long tracks him all the way and wins a free kick after being barged over by the winger.
76 minLess than 15 minutes of normal time to hold on for Swansea but it's going to feel like an eternity for Monk's side. The home supporters have been incredible though. The atmosphere is sensational, with all the home fans chanting their side on. They'll need all the help they can get.
77 minSouthampton's main tactic seems to be for them to get it wide and swing the ball into Pelle, who's won most of his aerial battles this afternoon. Fabianski plucks another cross out of the air.
78 minThe ball just keeps on coming into the box. Williams has been imperious throughout this second half, and what a baptism of fire for Fernandez on his full debut for the Saints!
80 minGOAL! Swansea 0-1 Southampton (Victor Wanyama)
80 minCould that be the winner? Swansea had defended so well until that moment! Pelle released the substitute, who isn't renowned for his goals, inside the box. He looked to have lost control of the ball when he struck it, but his right-footed toe poke flew into the far corner with just ten minutes remaining!
82 minYou can't say it hadn't been coming. Southampton have been on top for every single minute of this second half. They're now just keeping the ball against the very tired ten men of Swansea.
85 minSwansea come forward down the right flank and Sigurdsson's cross is cleared for a corner. But it's cleared at the near post.
86 minSUBSTITUTION: Marvin Emnes has come on for Swansea as Monk tries desperately to find an equaliser.
87 minThis is the first time in the half that Swansea have been able to mount any sustained pressure, but they'll have to act quickly if they're to find a goal. All 11 Southampton players are behind the ball.
88 minWilliams resorts to launching the ball long, but Southampton easily clear.
89 minBOOKING: Schneiderlin is shown a yellow card for a cynical foul on Montero, who had raced away down the left wing. The resulting free kick from Sigurdsson is far too high and Forster gathers with ease.
90 minInto the last minute of normal time now. The crowd are urging the Swans on, but an equaliser looks highly unlikely.
90 minFOUR MINUTES OF ADDED TIME: The home side have four minutes to find a leveller, but they need the ball first!
90+1 minCHANCE! Pelle should have put the game to be there. Tadic slotted a ball through to him in the left channel, but the striker's first touch was too heavy and Fabianski was out quickly off his line to smother the ball.
90+3 minCHANCE! Pelle has had so, so many chances today! Tadic again releases him down the left, but this time he slashes the ball wide of the near post.
90+3 minDavis now with another shot for Southampton from 20 yards, but it flies harmlessly over the bar.
90+3 minThe ball goes out of play for a throw in to Southampton and that should be it...
4.53pmFULL TIME: Swansea City 0-1 Southampton
4.55pmThe very meaning of a game of two halves. Swansea were dominant for 40 minutes until Bony was sent off for two bookable offences five minutes before the break. The second half was all about Southampton. For all their pressure , they struggled to break down the home side until substitute Victor Wanyama netted ten minutes from time.
4.57pmThat's Southampton's third win on the bounce and it moves them up to second in the Premier League table, two points behind leaders Chelsea. Swansea slip down two places to fifth.
5.05pmThat's all from me in terms of the live commentary, but make sure you stick around on Sports Mole for all the reaction to today's game, including analysis and thoughts from the players and managers. There's also live coverage of West Ham's game against Liverpool here and Simon Sinclair's cracking match report of the game from the Liberty Stadium here. Thanks for sticking around with me this afternoon!