Five arrests were made at the Cardiff City v Swansea City football derby on Sunday afternoon.
Two fans were arrested for invading the pitch at the game which saw the visitors Swansea beat their south Wales promotion rivals 1-0.
Three arrests were made after the game - one for a public order offence, one for assault and one for possession of drugs.
South Wales Police said the event was "well policed".
All five men arrested remain in police custody.
Inspector Dan Howe said: "We have made five arrests out of more than 27,000 fans at the game which is a relatively small number compared to previous years.
"Extra officers remain on duty in Cardiff and Swansea to deal with any later incidents that may arise following the match."
Cardiff City Stadium hosted the 59th meeting between the two rival sides.
Swansea's Marvin Emnes scored the winning goal in the second half.