"Thirty days should be necessary for a complete recovery," the club said in a statement.
Pirlo hurt his right hip during a friendly against league rivals AC Milan, the club said.
Juventus changed coaches after winning the Serie A title with Massimiliano Allegri replacing Antonio Conte, who guided the northerners to a third
Pirlo, 35, could return on October 5th for a much-anticipated clash against Roma, runners-up last season.
Juve open their title defence Saturday against Chievo in Verona.