Lewis Grabban scored his third goal in successive starts as Millwall stunned runaway League One leaders Swansea City with a victory at the Liberty Stadium.
This was a performance - and a night - to savour as The Lions turned the form book upside down to send The Swans to their first defeat in 19 games.
It was a happy homecoming for boss Kenny Jackett, who was returning to the club for the first time since parting company with Swansea 13 months ago.
Jackett made three changes to the side beaten by Bristol Rovers with Alan Dunne, Andy Frampton and Grabban in the starting line-up in place of Marcus Bignot and Ahmet Brkovic, whilst Dave Martin dropped to the bench with Adrian Forbes not involved.
Having already shared nine goals in their two previous meetings in the Johnstone's Paint Trophy and League One this season, this fixture again produced plenty of exciting, attacking football from both sides.
But no-one in the Liberty Stadium could have imagined that it would take just 28 seconds for the deadlock to be broken - especially the home fans who were stunned into silence when Grabban met Ali Fuseini's right wing cross and headed past Dorus de Vries.
Millwall could have doubled their lead just five minutes later, but this time Danny Senda surging run and cross from the right was met by Gary Alexander. Unfortunatrly the latter's low drive was held by keeper de Vries.
Swansea hit back with Ferrie Bodde struck a vicious shot narrowly wide before Andy Robinson saw his angled drive held by Evans in the visiting goal.
The Lions responded and a superb move ended with Grabban steaming into the area before sending a low shot agonisingly wide of the far post with de Vries stranded.
The Swans keeper was called into action again on 33 minutes when Jay Simpson wriggled past two players and hit a fierce drive that de Vries parried at full stretch.
Swansea had a penalty appeal turned down three minutes before half-time when the lively Butler was challenged by Frampton, but referee Keith Stroud waved away their appeals and awarded a corner instead.
No doubt a few choice words were delivered to the home side at half-time by manager Roberto Martinez and you would have expected Swansea to come flying out of the traps after the break.
But it was business as usual for Jackett's side, who created yet another opening on 48 minutes when Simpson set up Marc Laird, and the latter's piledriver was held by de Vries.
Lions keeper Evans was called into action after 55 minutes, and he pulled off a sensational save with his feet to deny Bodde's goalbound effort, with Darren Pratley contriving to blast the loose ball over from six yards with the goal at his mercy.
Swansea introduced Fabian Brandy for Kristian O'Leary just past the hour mark in a bid to liven up their attack.
But it was the visitors who struck for a second time when Simpson capitalised on a defensive mistake before drilling home from 16 yards to make it 2-0 in the 69th minute.
The celebrations had barely died down when Swansea were handed a lifeline by the referee, who awarded the softest of penalties for Fuseini's challenge on Brandy.
Up stepped Jason Scotland to make no mistake from the spot for his 21st goal of the season.
With 18 minutes left the home fans expected their team to pile on the pressure, and whilst Swansea enjoyed an equal amount of possession, they never really threatened an equaliser as Millwall worked tirelessly to deny them any clear openings.
In fact it was Jackett's men who could have added a third goal in the 90th minute when Simpson weaved his way forward before pulling the trigger. Although de Vries parried his shot, the ball fell invitingly for Marc Laird, who hit the follow-up straight at the keeper from three yards. Incredibly de Vries then fumbled, but Alexander just couldn't get enough purchase on the ball and the keeper collected.
Maybe a third goal would have been a tad greedy - but claiming the three points was so thoroughly deserved.
A night, most definitely, to savour for the 142 visiting fans whose vocal support once again was simply magnificent.

Swansea City: de Vries, Austin, O'Leary (Brandy, 64mins), Tate, Bodde, Britton, Pratley (Bauza, 85mins), Scotland, Robinson, Rangel, Butler. Subs not used: MacDonald, Way, Burgin.
Scorer: Scotland (72mins, pen)

Millwall: Evans, Senda, Frampton, Dunne (Bakayogo, 85mins), Robinson, Whitbread, Laird, Alexander, Grabban, Simpson, Fuseini. Subs not used: Edwards, Smith, Martin, Savage.
Bookings: Frampton (29mins), Simpson (78mins), Evans (90mins)
Scorers: Grabban (1min), Simpson (70mins)

Ref: K. Stroud
Att: 15,561 (away 142)