The Turin giant starts its quest for a ninth consecutive title in Parma on Saturday but could be without Sarri on the bench after the 60-year-old was diagnosed with pneumonia on Monday, AFP reported.
Sarri returns to Italy after one turbulent season in the Premier League with Chelsea, having previously coached his hometown team Napoli for three seasons.
Chain-smoking Sarri's appointment, in place of the clean-cut Massimiliano Allegri who had delivered the last five of the club’s Serie A titles, is a break in tradition for Juventus.
But after also ditching its iconic black and white striped jersey last season, the club is looking for a change in direction.
Despite its success Juventus has often been criticized for its boring defensive style of play.
Club bosses want a more attractive eye-catching style of football in an attempt to increase their fan base outside of Italy.
While Sarri's only major title was the Europa League last season with Chelsea, he promises to give serial Italian champion Juventus a more dynamic style of play.
Goalkeeper Gianluigi Buffon, returning to Turin after a season at Paris Saint-Germain, thinks the change of direction can pay off.
"Those who follow the same path will always achieve the same results, so Juve is seeking the Champions League and wanted to try breaking away toward pastures new," said the 41-year-old.
"Sarri is not a revolution, nor a gamble. He simply represents an untested path, a whole other story."
Among Juventus's rivals this season will be Carlo Ancelotti's Napoli and Inter Milan, now coached by former Juventus boss Antonio Conte.
But Juventus has spent big, giving Sarri a stellar squad to target a 36th Scudetto and its first Champions League title since 1996.
Cristiano Ronaldo, a player who Sarri insists "will make the difference," will again be central to attack with newly-signed Dutch star Matthijs de Ligt the jewel in defense alongside veterans Giorgio Chiellini and Leonardo Bonucci.
De Ligt's Ajax sent Juventus crashing out of the Champions League last season.
The midfield has been strengthened with PSG's Adrien Rabiot and former Arsenal star Aaron Ramsey, both acquired on free transfers but on large salaries.
For Juventus sporting director Fabio Paratici all the pieces are in place for Sarri to deliver another style of football.
"We're very happy with what has been done. We bought De Ligt, who all the top teams wanted," said Paratici.
"We managed to buy him, along with two big players on free transfers: Rabiot and Ramsey, who were courted by many.
"Juve has very high-level players in all departments, a squad of absolute value."
Juventus will be hoping these players and its new coach can implement the 'Sarriball' football philosophy: A fast-paced attacking style that impressed during his time with Napoli.
Brazilian left-back Alex Sandro insisted Sarri was already having an impact.
"We can't wait to start the season. We've already assimilated Sarri's mentality and, we know what to do.
"We all still have to improve naturally, but we are on the right path."
De Ligt also praised Sarri.
"He was one of the reasons that I wanted to join here, I've heard a lot of good things about him and I like his footballing philosophy and how he prepares his defense."
Sarri described coaching Juventus as "the crowning" moment of his 30-year managerial career.
"I arrive surrounded by skeptics, but then I always am. I had the same at Empoli, Napoli and Chelsea.
"In football, I know only one way of removing skepticism from the minds of people: By winning convincingly.
"I haven't won a lot, but I believe that having fun on the pitch doesn't stop you winning."