Like fine wine, Ibrahimovic is getting better with age and he showed with two goals at the Stadio San Paolo, where Milan defeated Napoli 3-1 to return to the top of the Serie A table.
Gattuso and Ibrahimovic were teammates at Milan between 2010 and 2012, when the pair helped the Rossoneri win their last Serie A title under Massimiliano Allegri in 2011.
Ibrahimovic’s brace in Naples took his tally for the season to 10 Serie A goals in just six games, and the 39-year-old is now the division’s top goalscorer.
Napoli manager Gattuso was full of praise for Ibrahimovic after the game as the Partonopei lost for the third time this season.
"Milan believe firmly in Ibra, they believe 100 per cent in what they are doing," Gattuso told Sky Sport Italia. "He seems I think even stronger now than he was 10, 12 years ago.
"They put the crosses in because they know he'll get on the end of them. What we did today was create lots of chances and not believe in them fully.
"It's about mentality. Football is about helping each other out, clubbing together, having a kind, reassuring word for your team-mate when they're struggling.
"There are too many people who act like professors, who want to teach you everything. This hurts me."
Napoli are sixth on the Serie A table, six points adrift of AC Milan.