The veteran attacker has urged his former team to move on after their Champions League elimination and has backed them to win another Scudetto
The Bianconeri were beaten 1-0 in Istanbul on matchday six of the competition and consequently ended third in Group B behind Real Madrid and the Turkish club, thus qualifying for the Europa League round of 32.
"I was really surprised by Juventus' elimination," he told La Gazzetta dello Sport. "I really believed in the team and I was quite upset by what happened.
"They still have the Europa League, though. Juventus should not take the Europa League lightly. And I'm not saying that just because the final is at the Juventus Stadium."
Del Piero then went on to discuss Juve's title credentials and stressed that it would be extraordinary if they could secure a third consecutive Serie A title.
"I don't know what Juve's main objective will be for 2014, but winning a third Scudetto in a row would be phenomenal."
Antonio Conte's men currently defend a five-point lead over second-placed Roma, whom they host in Turin on Sunday at 20:45CET.