Her skills were originally noticed by Barcelona Femenino's Andressa Alves da Silva, who invited the 6-year-old to watch a match.
Belgium and Portugal play in one of the two marquee clashes Sunday, while England and Germany square off Tuesday.
Ariana got to train with first team players, and even meet Luis Enrique.
Olley: England through, but must get better Highlights U.
We searched the world for passionate fans to help him predict the Champions League final between Juventus and Real Madrid.
The 7-year-old from Sydney is in demand across Europe.
We just couldn't help ourselves.
Denmark boss: Eriksen 'with us' Wales captain Bale storms off Previews: Portugal to stun Belgium? Laurens: Ronaldo equals record, Benzema stars Highlights U.