Barça took the lead inside the opening minutes through a powerful solo effort from Robert Lewandowski into the bottom corner beyond Unai Simón.
All eyes now turn to the San Siro, where the second leg will decide who reaches the final.
“Pedri and Ferran Torres have tested positive for COVID-19. The players are in good health and are isolated at home,” the club said.
The 28-year-old informed Spurs hierarchy of his desire to leave his boyhood club in search of trophies and advancement last month.
City are still first on the EPL table with 74 points in 32 games.
Spain storms into the final four of the league.
