Real, who announced on Tuesday that forward Mariano Diaz had tested positive for COVID-19, play at Manchester City in their Champions League last-16 second leg on August 7.
Sevilla, who said Wednesday an unnamed player had contracted the virus, take on Roma in a single-game Europa League last-16 tie in the German city of Duisburg the previous day.
“We are confident these cases will not affect the matches in question, in Manchester and Duisburg respectively,” the spokesperson said.
“UEFA is in contact with Real Madrid and Sevilla FC and is monitoring the two situations and the decisions of the competent Spanish authorities.”
The Champions League is ending with a ‘Final 8’ tournament in Lisbon after the completion of the last 16.
Man City lead Madrid 2-1 after the first leg at the Santiago Bernabeu, which was played in February.
Sevilla have halted training as a precaution, but Spanish champions Real are preparing as usual because Mariano has had no recent contact with his teammates.