Approximately one third of the Bergamo's population was clustered together in close proximity to watch the encounter with over 40,000 Atalanta fans packed the stands of the San Siro stadium, along with almost 2,500 traveling Valencia supporters, for last-16 first leg tie, which ended in a resounding 4-1 victory for the Italian club.
But the celebrations were cut short as Bergamo soon became the epicenter of Italy's coronavirus pandemic.
Dr. Luca Lorini, the Director of Intensive Care at the Hospital Giovanni XXIII, said the game could be to blame for the huge number of infections that hit Bergamo in the last weeks.
"I'm sure that 40 thousands people hugging and kissing each other at a distance of one centimeter for four times, as Atalanta scored four times.
"Those were an incredible accelerator for the infection," said Dr. Lorini.
The match was considered by many experts "Game Zero" and it was held two days before the first case of locally transmitted COVID-19 was confirmed in Italy.
The second leg was played at closed doors, but despite that many Atalanta fans travelled to Valencia.