For many, this weekend's game between Cardiff City and Swansea City is more than a football match. Seasoned football observers won't need telling that the south Wales derby is one of the most fierce matches in British football.
It may not have the religious undertone of the Rangers v Celtic games, it doesn't have the inter-city rivalry of the Manchester derby but it's a collision of two very different cities separated by 40 miles of motorway.
There seems to be bitterness on both sides that extends beyond football. Swansea fan Mal Pope says, "Swansea voted yes, Cardiff voted no, but they got the Senedd and we got a swimming pool!"
Thankfully the days of crowd trouble are firmly in the past, although a heavy police presence is still needed, but despite that there's a real reason for Welsh sport fans to be excited.
This is the first ever meeting between the two teams in the Premier League. The game will be beamed live across 220 countries and is expected to be the most-watched Welsh game of football in history.
And what about the football? Swansea are in their third Premier League season under famous manager Michael Laudrup, and having won the League Cup last term, are enjoying playing in European competition this season.
For many they'll be favourites against a Cardiff City side enjoying their first season in the League. They've beaten big spending Manchester City already but wins have been harder to come by more recently. Plus, speculation continues about the future of Malky Mackay, amid reports of tension between him and the billionaire owner Vincent Tan - the man responsible for the club colour change from blue to red.
The story and origins of the derby will be told in a new documentary to be broadcast at 10.35pm tonight on BBC One Wales called Bluebirds and Swans.
And you'll be able to listen to live commentary on BBC Radio Wales and BBC Radio Cymru… I can't wait!
