Real Madrid, 13-time record champions of Europe, will now try to salvage their season by emerging on top of a four-way battle for the Spanish domestic title.
Authorities used "sample pooling," meaning they collected residents' individual samples, and then processed 10 of them at once in a single nucleic acid test.
Lyon now run into Bayern Munich, who routed Barcelona 8-2 on Friday.
The other semi-final Tuesday is between Paris Saint-Germain and RB Leipzig en route to the August 23 final.