Champions League final ticket touts are to be targeted by police using facial recognition.
Juventus face Real Madrid in Saturday's sell-out at Cardiff's renamed National Stadium of Wales.
Supt Steve Furnham, from South Wales Police, said automatic facial recognition (AFR) will be used to track known criminals and suspects including touts.
He added the first arrest was made on Wednesday using AFR.
It was announced earlier this year that faces will be scanned at the stadium and Cardiff's central railway station but it was not previously known ticket touts would be on the radar.
"We have a significant intelligence cell set up which is linking to all the forces around the country," Mr Furnham said.
"We've been speaking to colleagues in Spain and Italy with their fans arriving here so there's significant sharing of information going on between all of those areas.
"For example, the automatic facial recognition is brand new to us and we're piloting it here for the first time.
"We're loading up faces of known criminals and people who we suspect commit offences such as ticket touting and that will be utilised on the day."
About 24,500 out of the 66,000 tickets available for the final have gone to sponsors.
The police is also investigating the theft of 13 tickets for the final from a hotel near Cardiff Airport and warned anyone buying tickets off the street could be refused entry to the stadium if they turn out to be stolen.
Juventus and Real Madrid fans have been allocated 18,000 tickets each while the rest went to the general public.
A further 100,000 people are expected in the city where there is also a fans' festival in Cardiff Bay.
Road closures have been put in place around the city and people are advised to check for updates and changes, with some closures brought forward.