Sarri was sacked and replaced by Andrea Pirlo on Saturday after their Champions League elimination by Lyon.
“I'd be lying if I said I wasn't surprised by this," Zola told Sky Sport Italia.
“It's fascinating and if the project works, it'll go down as a huge success story for the club. It's not an easy job, though, as Juventus are asking to win in a certain way.
“This is a courageous move from the club and based on the quality of the man, but Pirlo will need their support going forward. It's not simple, but I do think he can have real success."