The Italian, who left Stamford Bridge for Turin in June, underwent tests after being forced to sit out a training session on Monday due to persistent flu symptoms.
Sarri was not in attendance for Juve’s final pre-season friendly at Triestina on Saturday.
“Maurizio Sarri, after having observed rest over the weekend, was at the JTC Continassa today where he coordinated the work of his staff,” read a statement issued by the club, who begin their Serie A campaign at Parma this weekend.
“Unfortunately, he could not conduct the training on the field due to the persistence of his flu, which struck him over the course of last week.
“In the late afternoon, he underwent further tests that confirmed he has pneumonia, for which specific therapy has been prescribed.
“The coach has authorised the club to communicate his state of health.”
Juventus head coach Maurizio Sarri said Wojciech Szczesny remained Juventus’ first-choice goalkeeper – despite Gianluigi Buffon saving three penalties to help the Serie A champions to a 4-3 shoot-out win against Inter Milan after the match finished 1-1 in normal time.
Buffon, 41, re-joined the Old Lady this summer after a solitary season at PSG. He’d previously experienced a trophy laden 17-year stint in Turin.
Watch Sarri’s reaction above:
The Portugal international plundered 28 goals in his debut campaign for the Bianconeri following his move from Real Madrid, guiding them to an eighth successive Serie A title.
He picked up where he left off in Juve’s first pre-season game ahead of the 2019/20 season on Sunday, scoring a typically clinical goal in his side’s 3-2 International Champions Cup defeat to Tottenham.
“We need to be good as squad to help him because he is a player that can make the difference, and possibly he will make the difference,” said new boss Sarri.
“In the first game he already scored and he in addition had two or three clear chances, so he is the player that needs to make the difference and the remaining ten players will need to adjust.”