Pirlo returned to Juventus last week as the club's reserve team manager after completing his coaching badges and acquiring his UEFA Pro Licence.
The decision to rope the Italy legend was seen as a move to groom him for the first-team in the same manner as Pep Guardiola and Zinedine Zidane with the B teams of FC Barcelona and Real Madrid respectively.
However, following the Bianconeri's UEFA Champions League exit in the round of 16 to Lyon, Maurizio Sarri was given his marching orders, elevating Pirlo to the first-team hot seat without any managerial experience.
And former AC Milan Chief Executive Officer Adrian Galliani who worked with Pirlo during his time at the San Siro revealed the utter disbelief the 41-year-old was in after accepting the clubs offer this weekend.
"As soon as I heard Andrea on the phone, he was laughing like crazy,” Galliani told Corriere dello Sport.
"We met in Monzello on August 5 for Monza’s friendly with Juve's Under-19 team and I told him: "You'll see, Andrea, that you will have a great career. You're destined to be a successful coach.'
"But I didn't think it would only take him three days to get on the Juventus bench! I told him I imagined it would be in a few months. He laughed!
"If I had to define Andrea with a single word, I would say intelligent. And besides, he was a student. Andrea studied. Whether it was the opponent, the context of matches or situations within them. He'll do very well at Juventus."