Cardiff beat Swansea in first Premier League derby
Cardiff City won the first derby between Wales' two top football teams in the Premier League.
Steven Caulker headed the winner in the 1-0 victory over Swansea City in front of 27,000 at the Cardiff City stadium.
Swansea fans arrived in free buses laid on by the club, when they were handed their match tickets.
British Transport Police have been at stations along the south Wales main rail line as part of extensive security measures aimed at preventing trouble.
At rail stations with no CCTV, BTP officers wore body cameras, while plain-clothed and uniformed officers travelled on trains.
At 17:00 GMT, police reported no football-related arrests.
BTP Supt Andy Morgan said before the match: "Fans should not be concerned to see increased numbers of officers on the rail network on Sunday.
"While there are travel restrictions in place for the Swansea fans, trains in and out of Cardiff will be busy, as they are during any other Cardiff City home fixture.
"Having a high-visibility police presence helps provide additional reassurance for passengers and rail staff."
The "bubble" system has operated at previous derbies between the south Wales clubs, which sees visiting fans only being given match tickets if they travel on coaches, which are escorted to the stadium.
The buses carrying Swansea fans left the city's Liberty Stadium at around 12:30 GMT.
South Wales Police declined to give fuller details of the policing arrangements for the game.
The officer in command for the game, Supt Tony Smith, said: "South Wales Police is accustomed to policing large sporting events as a result of hosting the Wembley fixtures for six years and two Premier League seasons in Swansea.
"We work closely with clubs to develop policing arrangements for all fixtures throughout the season.
"As always, we want the focus ahead of the game to be on the football not the policing of the event. It is going to be a great occasion for south Wales and we hope the fans have a safe and enjoyable day."
The game is the 106th derby between the teams. At their last encounter three years ago, when both teams were in the Championship, Swansea City won 1-0 in Cardiff.
Sunday's game comes 101 years after the teams first met. The first derby, in 1912, ended in a 1-1 draw.
Last year Swansea fans produced a 192-page colour hardback book to mark the first derby game between the two teams.
Life-long Swansea City fan Peter Dawson, 57, unearthed the material on the game for the Swans 100 project, based at Swansea University.
The retired teacher said he thought the founders of the then Swansea Town club would be astounded at the success of their team and of the game over the following century.
He said: "When the original group of businessmen and supporters started the club, professional football was in its infancy.
"They were taking on rugby, the number one spectator sport.
"If you could go back in a time machine, like Doctor Who, and tell them that in 100 years' time their team would be playing in the top English division, playing Cardiff, and millions would be able to watch them, they would be astonished, and very proud."