Inter Milan have questioned the positive coronavirus test which ruled out defender Achraf Hakimi before their Champions League stalemate midweek.
The Moroccan international missed the 2-2 draw against Borussia Moenchengladbach after testing positive hours before kick-off.
The 21-year-old, who was asymptomatic, had tested negative the morning of the match and twice since.
"We are disappointed and regret the way events unfolded and the decisions we had to accept," Inter CAO Giuseppe Marotta told Sky Sports Italia before Saturday's league game in Genoa.
"On the morning the player was negative, while in the afternoon he became positive. This must not become an excuse but it created some upset.
"We must hope that in the future UEFA can be a little more precise with their communication."
Hakimi had tested negative twice since, "for which I have to thank our medical staff and the competent authorities," Marotta added.
"I'm back," Hakimi wrote on Twitter after his negative test on Saturday and travelled to Genoa to join his teammates.
The defender came off the bench in the second half as Inter Milan beat Genoa 2-0 to move third in the Serie A table.
Hakimi joined Inter from Real Madrid in the close-season after a successful two-year loan at Borussia Dortmund.