Former Chelsea boss Maurizio Sarri is being treated for pneumonia.
The 60-year-old Juventus coach spent Monday morning at the Italian club having missed a weekend friendly against Triestina because of what was initially thought to flu.
After feeling unwell, further tests diagnosed pneumonia and Juve confirmed treatment had begun.
Juventus visit Parma for their opening Serie A match on Saturday and it is not clear if Sarri will be in charge.
The veteran Italian joined Chelsea from Napoli in July 2018 and won the European League with the west London club during his one season at Stamford Bridge.
He succeeded compatriot Massimiliano Allegri at Juventus in June.