The midfielder is set to miss at least five Bianconeri games, along will a pair of Italy clashes, after he pulled a tendon this month.
An MRI has confirmed that the 35-year-old has pulled a tendon in his hip and is set to miss the first four or five Serie A games of the new season, as well as the first Champions League group stage game of 2014-15.
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The Bianconeri kick off their title defense on Saturday against Chievo Verona but Massimiliano Allegri will have to rely on others to get his debut season in charge off to a solid start, though he is already set to be without Arturo Vidal, Giorgio Chiellini, Andrea Barzagli and Alvaro Morata.
The former AC Milan talisman featured 45 times under Antonio Conte in 2013-14 and has helped to navigate Juventus to three successive Scudetti since his arrival in 2011 from San Siro.
Pirlo has yet to confirm if he will retire from the national team, which Conte now coaches, but he will definitely not be involved in Italy's upcoming internationals in early September against Netherlands (a friendly) and Norway (a Euro 2016 qualifier).