An 80-year-old bystander has been taken to hospital after an alleged fight between two men at the Principality Stadium.
Police said the incident happened during the Wales v New Zealand game on Saturday, and the two men involved, aged 20 and 32, have been arrested for assault.
In a statement, South Wales Police said: "Shortly before 4.30pm yesterday (Saturday 5 November), South Wales Police was called to reports of an altercation between two men at the Principality Stadium.
"The two men involved, aged 20 and 32, were arrested for assault and remain in police custody.
"An 80-year-old male bystander was injured and was taken to hospital."
The force say enquiries are ongoing and have appealed for anybody with information to contact South Wales Police, quoting 2200375175.