Gennaro Gattuso warned Juventus head coach Andrea Pirlo that his illustrious playing career will count for little in his new job.
Pirlo, who has not had a coaching job and only took over as Juve's Under-23s boss last week, was handed the reins in Turin on Saturday in the wake of Maurizio Sarri's dismissal.
The former midfielder – who won four Serie A titles, one Coppa Italia and two Supercoppa Italiana during a four-year spell with Juve – has signed a two-year deal.
However, Gattuso, who played alongside Pirlo at Milan and for Italy, provided an honest assessment of the job's difficulties for his former team-mate.
"Well he's screwed now… That's the job," Gattuso told Sky Italia following Napoli's defeat to Barcelona in the Champions League.
"He's lucky to be starting at Juventus, but this profession is one where a great playing career is not enough.
"You have to study, to work hard, and you don't get much sleep."
Gattuso's first job in coaching came at FC Sion, with the 42-year-old then having spells at Palermo, OFI Crete and Pisa before he took charge of Milan's youth team in 2017.
He was promoted to first-team head coach following Vincenzo Montella's sacking later that year, though he was dismissed at the end of the 2018-19 campaign after a fifth-placed finish, going on to replace Carlo Ancelotti at Napoli, who he guided to the Coppa Italia title this term.
"Being a player and being a coach is really not the same thing at all," Gattuso added.
"It's a totally different profession and we can't learn it just from books, we need to get in there and work hard. It's a different world."