Gattuso and Pirlo forged one of the most formidable midfield partnerships at Milan under Carlo Ancelotti, and also played alongside each other with the Italian national team.
Pirlo announced his retirement from football on Monday aged 38, ending his illustrious career at MLS side New York City.
When Gattuso was asked on Tuesday if he made Pirlo a better footballer, he couldn't help but chuckle.
"Don’t talk nonsense; let’s not confuse Nutella with shit," the Milan Primavera boss told Radio 24.
“When I saw him play it made me think I had to change profession. Nobody knows that better than me, because I started playing with him at Italy U15 level and then all the youth teams after that.
“It wasn’t only about his quality, but he was an animal covering 1,000 metres – he had this athletic quality which is why he played until this age ."
Gattuso also spoke to TV show CheTempoCheFa and shared an anecdote of how Pirlo offered his team-mate's sister to Milan's club president Adriano Galliani.
"You see him, the face of an angel, but he is a son of a bitch; always makes jokes, always breaks the boxes, does not stand still," Gattuso said.
"One day I was eating at Milanello, I had the bright idea to leave my phone on the table. He sent a text message to Galliani and [sports manager Ariedo] Braida offering them my sister."
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