The Partenopei started strongly but found themselves 2-0 after 50 minutes of action, only for a brace from Piotr Zielinski and a late winner from Dries Mertens to turn the game completely on its head.
Speaking after the match, Ancelotti had his say on what gave his side the edge over Gennaro Gattuso's Milan (via CalcioMercato).
He said: “Sometimes we can switch to 4-4-2, these players have a lot of knowledge. It’s a paradox but we became more offensive when we found balance in midfield pressing Biglia. Mertens? He is a kind of attacking midfielder. He is very good with short combinations. We asked him to play a bit more on the left with Insigne playing wider.”
Ancelotti also took time during his post-match interview to defend midfielder and club legend Marek Hamsik, who looked off the pace for the second consecutive game after delivering a drab performance in last week's narrow victory over Lazio.
Ancelotti added: “Hamsik? He will improve when we will play a little wider and more vertically. His qualities will emerge, I am happy for what he is doing.”
Napoli face Sampdoria in an away fixture next weekend, giving Ancelotti's side a potential respite after a tricky opening two fixtures that saw them take on two of last season's top six.
Ancelotti is in his first season as Napoli manager, having replaced Chelsea-bound Maurizio Sarri at the end of the 2017/18 season.