Cardiff City and Swansea City both secured their places in the Championship play-offs on a dramatic final day of the season - and now there is the tantalising possibility of a south Wales derby at Wembley.
There is still some way to go before the old foes can contemplate locking horns in a play-off final, with Cardiff facing Fulham and the Swans taking on Brentford in their semi-finals.
But should they both triumph, their fierce rivalry would add even more intrigue to the already enormous stakes of a Championship play-off final.
Cardiff and Swansea secured their top-six places in contrasting styles: the Bluebirds coasted past Hull City while the Swans were involved in one of the most eventful Championship finales of all time as they beat Reading to overtake Nottingham Forest.
So how will the two Welsh clubs be feeling now?
Ahead of what will be a seventh play-off campaign for each side, BBC Sport Wales looks at Cardiff and Swansea's play-off histories and their hopes of promotion this time around.
Cardiff's years of misery - and one success story
The mere mention of play-offs used to send shivers down the spines of Cardiff supporters.
Between 2010 and 2012 the Bluebirds missed out on promotion to the Premier League in three successive seasons.
Perhaps most painful was the 3-2 loss to Blackpool in the 2010 Championship play-off final, before a semi-final defeat against Reading in 2011.
Then in 2012 a comprehensive beating at the hands of West Ham United proved to be Cardiff's last match before owner Vincent Tan's highly divisive decision to change the club's shirts from blue to red.
Some of those rifts have healed since Cardiff returned to blue, but long-time followers will recall play-off anguish further back in time.
The Bluebirds' first play-off campaign in 1997 ended with semi-final defeat against Northampton Town in the old Division Three, and they fell at the same hurdle against Stoke City in Division Two in 2002.
But a year later Cardiff clinched promotion to Division One - now the Championship - with their solitary play-off success from six attempts.
While Wembley was being rebuilt, Cardiff were able to play in their own city as they faced Queen's Park Rangers at the Millennium Stadium.
Then Wales centre-back Danny Gabbidon, who was a part of the Bluebirds side beaten by Stoke the previous season, was at the heart of a Cardiff defence which held firm in a nervy 1-0 win against QPR.
"We just felt relief because we won," Gabbidon recalls.
"The whole build-up is not enjoyable at all. You just want the game to come around. There's just so much pressure on the games.
"The prize is massive and you know if you make a mistake you could cost your team promotion. The games can be really cagey and it's difficult to perform to your best.
"I was just happy to win. It was the worst game ever - Andy Campbell scored in extra time - but it doesn't matter how you get over the line."
Now a pundit with BBC Sport Wales, Gabbidon still watches Cardiff regularly and he believes their recent good form - they have the third best record in the Championship since the season's resumption - will stand them in good stead against Fulham.
"They hit the ground running from the lockdown and they've got results when they've needed to," he says.
"They've got it right at the right time. It's been a slow build-up through the season and they've got better and better, improved with every game.
"You have to give massive credit to the players and even more so the manager, Neil Harris.
"It's important as a player you don't think about the past too much. It's about being right for three games."
Joy and pain for Swansea - with the finest hour in 2011
Swansea have tasted play-off defeat on four occasions, but have also sampled the euphoria that comes with winning promotion the long way round.
They triumphed in the early days of the play-offs, when Terry Yorath's team climbed into Division Three thanks to a two-legged victory over Torquay United in 1988.
But hopes of promotion to the second tier in 1993 were ended by 3-2 aggregate defeat by West Bromwich Albion, and there was more misery four years later when Jan Molby's Swansea were beaten by a late Northampton free-kick at Wembley.
In 2006 Swansea did what they hope to do now by overcoming Brentford in the play-off semi-finals.
But in the Millennium Stadium final, Alan Tate - who is now on the coaching staff at the Liberty Stadium - and Adebayo Akinfenwa missed penalties in defeat by Barnsley after Kenny Jackett's side had wasted chances to win before the shootout.
Swansea's finest play-off hour was their most recent, in the Championship in 2011.
Having overcome Nottingham Forest in a pulsating semi-final - the second leg is arguably the most memorable game the Liberty has seen - Brendan Rodgers' team faced his former club Reading at Wembley.
They were 3-0 up at half-time thanks to two Scott Sinclair goals and a sweet Stephen Dobbie strike, before the Royals came back to 3-2 after the break.
Swansea wobbled, with skipper Garry Monk making the block of his life to keep them ahead before Sinclair's second penalty of the day sealed victory.
"The feeling we had afterwards, being the first Welsh team to reach the Premier League, was amazing," says Dobbie.
"The changing room afterwards was fantastic, then you go upstairs - still with your strip on - to see your family. Then the party really starts when you get on the bus back to Swansea. They are memories I will never forget.
"It was probably the best day in my football career."
Dobbie watched on with a smile as Swansea booked a place in this year's play-offs, particularly as former team-mate Wayne Routledge was a central figure in their win over Reading with two of their four goals.
He says Steve Cooper's team "definitely have a chance" and he should know.
Dobbie, 37, who is still playing for Queen of the South, also won the Championship play-off final with Blackpool and was part of the Crystal Palace squad who triumphed in 2013.
"I remember at Blackpool [in 2010] we just pipped Swansea to sixth and we were playing teams who had finished above us, but it's just a cup scenario in the play-offs," he adds.
"You need a bit of luck, then it's all about who wants it. Any promotion is obviously special, but the play-off final - the whole day - is a momentous occasion if you win."