The Italy international picked the ball up wide on the left before exchanging passes with the Belgian and slotting past Ederson from six yards.
It was a lovely move that went to prove that Pep Guardiola's praise for Napoli pre-match was entirely deserved.
The goal took Insigne's tally to two in four games in the Champions League so far this season.
Check out the goal for yourself below:
Nice assist by Mertens. Insigne with the first goal of the game for Napoli#NAPMCI #UCL #ChampionsLeague #ManchesterCity pic.twitter.com/rS7iFnTCq7
— After The Whistle (@gcratw) 1 November 2017