Match ends, Southampton 3, Swansea City 1.
Virgil van Dijk scored his first goal for Southampton who eased to a comfortable victory over Swansea.
The Dutch centre-back, who signed from Celtic in the summer for £13m, headed in at the near post to give the Saints an 11th minute lead.
Dusan Tadic made it 2-0 after the break when his attempted cross went in off Ki Sung-yueng before Sadio Mane slotted in the third from inside the area.
Gylfi Sigurdsson scored a penalty for the Swans in the 83rd minute.
Referee Roger East pointed to the spot after Jose Fonte had pulled down Neil Taylor, although Swans forward Eder put the ball in the net unaware the whistle had been blown.
Southampton's second league win of the season sees them move to nine points, level with the Swans who have now not won in three.
Saints forwards in unison
It was a day when everything clicked for Southampton's front men.
Graziano Pelle failed to add to his four goals this season, but he was integral to his side's success. The 6ft 4in Italian was a nuisance in the air, winning 50% of a team-high eight aerial duels, and was the pick of the Southampton XI when it came to passing stats - making 31 in the opposition half.
Of course it was his contribution to the goals that made the biggest impact. His first was a lovely lofted ball for Tadic, whose intended square pass for Mane was deflected in.
And he had a big hand in Mane's goal when his strike came off the boot of defender Ashley Williams and arrived at the feet of the impressive Mane, who produced a delightfully composed finish.
Swans at sea?
Perhaps not quite, because the team performed well, they just lacked someone to provide a clinical finish.
Striker Bafetimbi Gomis, who has scored four in the league so far this season, went missing before he was found and substituted at half-time. His contribution? Seven passes in total, no efforts on goal and what is now his obligatory stray into an offside position.
Fellow attacking player Andre Ayew was busy, but not so much in the final third as he was involved in a team-high 17 duels in midfield - almost twice as many as his team-mates.
Gylfi Sigurdsson impressed in flashes and of course scored the penalty that gave the Swans a glimmer. Although that is all it was.
Perhaps Garry Monk needs to rethink his attacking strategy because there was not much support for either lone striker - Gomis and substitute Eder.
Swansea boss Garry Monk:
"We have not been up to scratch in the last two away games. We were not focused enough and possibly made too many mistakes today.
"They punished us and we never recovered from that. All three goals were disappointing. It was poor decision-making and individual errors. It's not good enough for the standard we have set here at the club.
"We pushed to try to get back. We got the goal then had a couple of chances to make it 3-2. It's difficult to assess straight after the game what went wrong."
Southampton manager Ronald Koeman:
"It was not a very good performance today. The way we played is not the level we expect. But we were much more clinical today than normally. That was the difference between Swansea and Southampton.
"You need good communication in the team but we had some problems - they were allowed four or five good shots from outside the area.
"At 3-0 up we should have dominated more in the last 30 minutes. We were too much in mind to defend the result rather than go and score more. I like to win and play good football."
Man of the match - Graziano Pelle (Southampton)
The stats you need to know
- Southampton have lost only one of their seven Premier League games versus Swansea (W4 D2).
- The Saints have won six of their last nine PL games at St Mary's, losing two (D1).
- Swansea have won just three of their 17 Premier League games in the month of September (W3 D4 L10).
- Sadio Mane has scored or assisted eight goals in his last five Premier League appearances at St Mary's (four goals, four assists).
- Dusan Tadic has scored three goals in his last three Premier League appearances for Southampton on home soil.
Southampton have a tricky test at Stamford Bridge for next Saturday's evening game against Chelsea. Swansea will look to get back in the winning habit at home to Tottenham next Sunday.
- 2Cédric Soares
- 6José FonteBooked at 83mins
- 17van Dijk
- 12WanyamaBooked at 43mins
- 10ManéSubstituted forJuanmiat 86'minutes
- 8DavisSubstituted forRomeuat 62'minutesBooked at 81mins
- 11TadicSubstituted forRodriguezat 74'minutes
- 4Ki Sung-yueng
- 24CorkSubstituted forMonteroat 45'minutes
- 8ShelveyBooked at 76minsSubstituted forBrittonat 80'minutes
- 10A Ayew
- 23G Sigurdsson
- 18GomisSubstituted forMacedo Lopesat 45'minutes
- 17Macedo Lopes
- Roger East
- Shots on Target
Second Half ends, Southampton 3, Swansea City 1.
Attempt missed. Graziano Pellè (Southampton) left footed shot from the centre of the box is high and wide to the left. Assisted by Juanmi.
Offside, Swansea City. Gylfi Sigurdsson tries a through ball, but Ashley Williams is caught offside.
Foul by Federico Fernández (Swansea City).
Graziano Pellè (Southampton) wins a free kick in the attacking half.
Attempt saved. André Ayew (Swansea City) header from the centre of the box is saved in the centre of the goal.
Eder (Swansea City) wins a free kick on the left wing.
Foul by Oriol Romeu (Southampton).
Substitution, Southampton. Juanmi replaces Sadio Mané.
Goal! Southampton 3, Swansea City 1. Gylfi Sigurdsson (Swansea City) converts the penalty with a right footed shot to the high centre of the goal.
Jose Fonte (Southampton) is shown the yellow card for a bad foul.
Penalty Swansea City. Neil Taylor draws a foul in the penalty area.
Penalty conceded by Jose Fonte (Southampton) after a foul in the penalty area.
Oriol Romeu (Southampton) is shown the yellow card for a bad foul.
Eder (Swansea City) wins a free kick in the attacking half.
Foul by Oriol Romeu (Southampton).
Corner, Southampton. Conceded by Federico Fernández.
Substitution, Swansea City. Leon Britton replaces Jonjo Shelvey.
Foul by André Ayew (Swansea City).