Del Piero, 35, has vast experience of playing against English sides over the years.
And he knows City will be fired up for the clash in front of their own fans at Eastlands.
Speaking ahead of a training session, he said: "Manchester City are in excellent shape and it will be very hard for us. It always is when you are in England.
"They have invested heavily and one of the reasons they can be successful is that they have a great squad of players."
Juventus, like City, are in transition with a new coach in Luigi Del Neri, who was appointed in May, and are struggling to get going in Serie A.
Del Piero said: "We have a good base to build on and are at the beginning of a journey. Hopefully we our results will improve as time goes on."
Juventus face a crunch match against Inter Milan on Sunday but Del Neri is thinking only of their Group A meeting with City.
He said: "I am only interested in tomorrow not the following match. We will see then if we have improved.
"A new team always make mistakes. You not only need to fix the problems but also to focus on what you do well."
Meanwhile Giorgio Chiellini is set to sign a two-year contract extension with Juventus in the next few weeks.
The Italy international's current deal expires in June 2012 and Real Madrid were among the top European clubs keen to acquire Chiellini's services this summer.
A statement from the club read: "The club executives met with Giorgio Chiellini.
"The two sides are very close to reaching an agreement for a contract renewal.
"The details of the deal will be revealed in a few weeks' time."
The 26-year-old centre-back has been a regular since joining the Bianconeri in the summer of 2005 from Fiorentina.
Last season, Chiellini was named Serie A defender of the year for the second time running for his solid performances.