Southampton set a new club record of 21 games without defeat thanks to a 3-1 victory on Russell Martin’s first return to Swansea City.
The Saints climb to second in the Championship having outclassed Swansea in the first half, Che Adams putting them ahead from close range only six minutes in.
Will Smallbone tapped in the second goal before Swansea responded against the run of play through a Jamie Paterson header.
But Southampton quickly re-established their control of the contest as Flynn Downes’ 20-yard drive deflected into the net.
Swansea rallied in the closing stages as substitute Jerry Yates and Paterson both hit the woodwork, but their failure to take the late chances allowed Southampton to hold on for three points with comfort.
Southampton’s run of 21 matches unbeaten in all competitions eclipses their previous best since they entered the Football League in 1920, a 20-game sequence in 1921.
This was a sweet result for Southampton boss Martin, who was given a warm welcome on his first trip back to Wales since leaving his role as Swansea head coach to take over at St Mary’s last June.
But it was a testing afternoon for Luke Williams, whose team could have no complaints after defeat in his first home league game as Swansea boss.
Martin had enjoyed his first reunion with Swansea on 26 December, when the Welsh side crumbled after a bright start and were eventually thumped 5-0.
Swansea have since appointed Williams, who was on the club’s staff under Martin in the 2021-22 season, but it quickly became apparent this would be another day where Southampton dominated for long spells.
Adams had already missed one decent chance, slicing wide from Ryan Manning’s cross, by the time he swept home on the rebound after Carl Rushworth had parried Stuart Armstrong’s shot into his path.
Rushworth then made a brilliant double stop to deny Ryan Fraser and then Adam Armstrong, but Southampton’s second arrived when Stuart Armstrong – who had appeared to be offside – crossed from the left and the unmarked Smallbone tapped in from point-blank range.
Adam Armstrong drew another save from Rushworth as Southampton swarmed all over their hosts, yet Swansea briefly came back into the contest thanks to their best move of the first half.
When Harrison Ashby crossed from the right, Gavin Bazunu collided with Jamal Lowe – who may have been offside – leaving Liam Cullen to loft the ball across goal for Paterson to head home.
Yet Swansea did not have momentum for long, as Downes marked his 25th birthday with his first Southampton goal.
Former Swansea midfielder Downes did not celebrate, but Southampton were smiling again.
The contest was more even after the break, with Paterson going close to a second Swansea goal and substitute Charlie Patino shooting wastefully wide.
Southampton had chances too, with Rushworth’s outstretched hand denying Adams a tap-in and Fraser lifting a shot over the bar when unmarked at the far post.
Swansea then conjured their best spell of the contest as the clock ticked down, with Yates turning Paterson’s cross-shot against the post before another Paterson effort was pushed on to the other post by the diving Bazunu.
Yannick Bolasie went close twice as Swansea missed the chance to make things interesting in the closing minutes.
Swansea City head coach Luke Williams:
“First half we were too deep, far too deep. Southampton could push the ball around, take their time and wait for the space and they did that brilliantly.
“Second half, the difference is we play higher up the pitch and we won the ball higher up the pitch. We were able to create chances.
“I am pleased we were able to show a better performance second half, but very disappointed with the first half.
“They are trying to force you to make errors and we fell into too many of those traps in the first half.
“Second half we hit the woodwork twice. We had very good opportunities and fluffed our lines a little bit.”
Southampton manager Russell Martin:
“It’s a nice moment [to break the record]. I’m really grateful to the players for what they’ve done, the courage they’ve shown on the back of what was a tough spell as well for us as a group. I am immensely proud.
“The way they did it in the first half – that was one of the best performances I’ve ever been involved in as coach. It was incredible.
“It’s taken a lot of hard work and they’ve really stepped up. They’ve written themselves in the history books – and let’s keep it going.
“I think it will have more significance, importance and standing if we achieve what we want to at the end of the season, otherwise it will be just something we’ve achieved together.”