Camila Cabello put on a great performance before the UEFA Champions League Final this weekend -- pristine in presentation ... but exactly the opposite of what was unfolding outside.
The singer was tapped for the opening ceremony show at the Stade de France in Saint-Denis just north of Paris -- where Real Madrid was facing off against Liverpool in a huge showdown between Europe's best soccer teams ... a must-see match fans were dying to see.
That might even be literal, because tons of prospective gamers were outside the stadium shortly before kickoff -- while Camila was doing her gig -- and desperately trying to get in by any means necessary .