Joel Piroe’s 18th goal of the season saw Swansea City back up their south Wales derby triumph with another impressive victory on their travels at Millwall.

The Lions have one of the best defensive home records in the Championship but Piroe’s right-footed strike just moments into the second half proved the difference at The Den.

And, while there may not have been the emphatic scoreline that underlined the result at Cardiff, this was another exciting glimpse at the progress being made under Russell Martin.

The margin of victory could, and perhaps should, have been greater as the Swans dominated possession and showed excellent control and accuracy in much of their play against a home side still harbouring play-off aspirations.

The Swans had shown two changes from the wonderful derby win over Cardiff as Ryan Manning and Jay Fulton came in for Jamie Paterson and Flynn Downes respectively, with the latter missing through injury.

The concern would have been that the physical and emotional energy expended in the humbling of their south Wales rivals would have an impact on matters in south-east London given the quick turnaround.

But such concerns would prove groundless and the Swans had some bright moments from the off, with Michael Obafemi so close to getting onto the end of a lovely cross-field pass from Piroe.

At the other end Dan Ballard headed over from a corner, while Benik Afobe made a poor contact with a left-footed effort from a swift counter.

But Swansea were finding their rhythm and it took an outstanding save from Bartosz Bialkowski to prevent Obafemi’s shot finding the net after a magnificent flowing move that had pulled the home side to pieces.

That chance kicked off a period where the visitors looked comfortable and in control of proceedings, and Bialkowski was forced into action again by an awkward bouncing strike from Fulton after more slick build-up play.

Piroe then had appeals for a penalty turned down, while the lively Obafemi saw an effort blocked after excellent direct forward play worked him into the Millwall area.

The Swans were playing some excellent stuff, but they needed an important block from Joel Latibeaudiere to ensure Jed Wallace’s strike flew wide of Andy Fisher’s goal.

The away side swept straight up the other end, Piroe’s turn and low shot forcing Bialkowski into a smart stop as the half ended goalless.

But the wait for a goal did not last long into the second half, as the Swans took the lead with just 50 seconds on the clock.

It came via a superb instinctive finish from Piroe, who lashed home with his right foot after Cyrus Christie’s cross had come to him.

Swansea were soon on the front foot again, Obafemi working room for a strike that was well-blocked by Murray Wallace.

Bialkowski then held a glanced finish from Obafemi after smart work by Hannes Wolf, Christie and Manning with Swansea having almost a complete stranglehold on proceedings.

George Saville volleyed wastefully wide from a rare Millwall opening at the other end but the hour mark came and went with the Swans still a goal to the good.

The frustrations of the home side and crowd were clear to see and hear, and Kyle Naughton added to them with a cheeky nutmeg as further attempts at preventing the flow of Swansea possession foundered again.

However, there were frustrations for Swansea too moments later when Christie waited far too long to release the ball to fellow white shirts after being found in oceans of space down the right by Fulton.

But Millwall were beginning to have a few moments of joy in transition, with Fisher doing well to tip a Jed Wallace effort wide.

Obafemi then fired wide after showing good footwork from Naughton’s astute pass into his feet.

Millwall pressed in desperate search of a leveller, with Matt Grimes making a brilliant far-post clearance before a deflection flew just wide with Fisher stranded.

But it made no difference to the final outcome as the Swans extended their unbeaten run at this venue, which stretches back to 2007.

Millwall: Bartosz Bialkowski, Danny McNamara, Murray Wallace, Jake Cooper (captain), Jed Wallace (Sheyi Ojo 79), Tom Bradshaw (Oliver Burke 60), Scott Malone, George Saville (Maikel Kieftenbeld 60), Benik Afobe, Billy Mitchell, Dan Ballard.

Unused Substitutes: George Long, Ryan Leonard, George Evans, Tyler Burey.

Swansea City: Andy Fisher; Ben Cabango, Kyle Naughton, Joel Latibeaudiere; Cyrus Christie, Jay Fulton (Korey Smith 79), Matt Grimes (captain), Ryan Manning; Joel Piroe (Jamie Paterson 78), Hannes Wolf (Olivier Ntcham 63); Michael Obafemi.

Unused Substitutes: Ben Hamer, Kyle Joseph, Nathanael Ogbeta, Cameron Congreve.

Referee: Andy Davies