Ireland striker Michael Obafemi scored twice as Swansea made South Wales derby history by thrashing Cardiff 4-0 to secure the first league double in 110 years of the fixture.
Ben Cabango and Hannes Wolf were also on target in this one-sided Championship contest in the Welsh capital.
It was a particularly sweet moment for Wales defender Cabango, who was born and raised just a few miles away from the Cardiff City Stadium.
Swansea won the reverse fixture in October 3-0, a result which paved the way for Mick McCarthy's departure and the appointment of Steve Morison.
The peculiar statistic that no side had ever won both matches in the same league campaign would not have provided Swansea with confidence ahead of a game played for the first time at 3pm on a Saturday since 1991.
Obafemi now has eight goals in 11 games after scoring just once in his first 15 Swansea appearances.
On Obafemi's form, Swansea manager Russell Martin said: "I put it down to finding a level of consistency in his daily approach. To accept criticism and be honest with me and his team-mates.
“He’s dropped his guard and been himself. Just worked really hard, good attitude and the rest comes with that.”
An own goal from Ireland defender John Egan secured a 1-0 victory for Stoke as they dealt Sheffield United's playoff hopes a blow.
The Potters, who have now won two consecutive league games for the first time since November, missed a sequence of glorious opportunities before eventually breaking the deadlock with a slice of fortune.
Now without a win in five games on their travels, the promotion-hopeful Blades struggled to assert themselves as they slipped out of the playoff fray.
Aleksandar Mitrovic took his tally for the season to 37 goals with a brace in Fulham's 2-0 victory at QPR.
The Serbia striker set the runaway leaders on their way in the 14th minute when he slotted home from Fabio Carvalho’s cutback.
Having brought a number of saves from former Ireland goalkeeper Keiren Westwood, including with a stunning backheeled effort, Mitrovic finally made it two from the penalty spot after Lee Wallace was adjudged to have handled in the area.
Victory maintained the Cottagers' eight-point advantage at the top of the Championship, with second-placed Bournemouth holding on for a 3-2 win at home to Bristol City.
The visitors took an early lead when Matty James's corner was headed in by defender Rob Atkinson.
Bournemouth levelled five minutes before the break when Dominic Solanke scored his 24th league goal of the season.
Lewis Cook put the Cherries in front seven minutes into the second half with a stunning 25-yard strike and Siriki Dembele sealed the points nine minutes from time with a fine solo effort.
Andreas Weimann scored a consolation for the Robins in stoppage time.
Middlesbrough moved up to fifth with a convincing 4-0 win at rock-bottom Peterborough.
Marcus Tavernier’s first-time strike into the top corner opened the scoring and Folarin Balogun doubled Boro’s lead early in the second half.
Josh Coburn made it three eight minutes from time and Duncan Watmore wrapped up the win at the death with an emphatic finish.
Brennan Johnson scored twice as Nottingham Forest continued their playoff charge with a stunning 4-1 win at Blackpool.
A double from Johnson – the second of which came after a dreadful goalkeeping error from Dan Grimshaw – a Philip Zinckernagel effort and a Sam Surridge strike handed the visitors the points. Callum Connelly scored a last-minute consolation for Blackpool.
Luton snatched a point in an entertaining 2-2 draw at home to Millwall.
Tom Bradshaw put the Lions in front after 25 minutes with a half-volley from a Jed Wallace pass, but Luton levelled eight minutes later when Elijah Adebayo curled home via a post.
Benik Afobe thought he had won it for Millwall, but Jake Cooper turned a wicked Robert Snodgrass free-kick past his own goalkeeper to earn the Hatters a share of the spoils.
Viktor Gyokeres equalised for Coventry in the ninth minute of stoppage-time as they held Blackburn to a 2-2 draw.
Harry Pickering’s own goal was cancelled out by Bradley Dack’s first goal since March 2021.
Scott Wharton made it 2-1 eight minutes from time, but late drama saw Gyokeres snatch a point for the home side.
At the bottom, Derby moved within six points of Reading with a 1-0 win against Preston.
North End were reduced to 10 men after 32 minutes when Liam Lindsay was shown a straight red card for a last-man challenge on Tom Lawrence.
Derby saw Max Bird dismissed early in the second half for a wild challenge on Ben Whiteman but snatched victory with an 81st-minute strike from Ravel Morrison.
Barnsley and the Reading played out a 1-1 draw.
Carlton Morris drilled the Reds in front from Amine Bassi's pass after five minutes.
Barnsley rode their luck, but Josh Laurent levelled after 82 minutes with a close-range finish.