The respective supporters' trusts of Cardiff and Swansea have issued an early call for fans of the rival clubs to behave themselves at next month's south Wales derby.
The November 3 meeting at Cardiff City Stadium will be the first time the club's have clashed in the top flight.
Even though the fixture has always attracted attention, this time the glare of a global Premier League television audience of millions around the world will put the Swans and Bluebirds in the spotlight like never before.
The derby has previously seen trouble between the rival sets of supporters and, at one point, the Football Association of Wales banned away fans from attending.
Rival fans clashed with police after a League Cup encounter in 2008, while later in the same season referee Mike Dean was struck by a coin at Ninian Park.
However, the two supporters' trusts hope this season's meetings will be remembered for the action on the field.
Phil Sumbler, chairman of Swansea City Supporters' Trust, said: "It will be a passionate and noisy encounter and a chance for fans on both sides to showcase what is best about south Wales' two Premier League clubs.
"It is important to ensure all post-match discussions are about the action on the football pitch and I hope all in the stadium enjoy what will be a fantastic occasion."
Tim Hartley, chairman of the Cardiff City Supporters' Trust, added: "These are exciting days for Welsh football.
"We have been looking forward to this fixture for years and the match will be a showcase for the two cities and also for Wales.
"Cardiff v Swansea has always been a passionate encounter with plenty of banter between supporters. In the past this has sometimes gone too far so it is important that fans do not overstep the mark and show each other respect.
"We want the derby to be remembered for all the right reasons - plenty of thrills and high quality football between two great rivals played in the right spirit.
"So we are saying to fans, support your team, but please ensure at all times you do it in the right way."