The San Paolo club are in pole position in a tightly contested Scudetto race after winning 10 of their opening 12 league games this season.
Napoli's only defeats have come in the Champions League, but Sarri has made clear that domestic glory is at the forefront of the club's ambitions this season.
One of Sarri's many great innovations at Napoli has been the transformation of Mertens from tricky winger to devastating finisher – the Belgium international has 42 goals in 53 games since being converted last October.
"Sarri taught me football," Mertens told Corriere dello Sport. "He is a coach I really like, well-prepared and even scientific in the way he analyses games.
"The thing I love the most about his style of football is the way he organises the phases when we are off the ball and structures the pressure we put on opponents when they've got the ball at their feet.
"It feels like he has already played the game out in his head and on the field you have an extra man."
Napoli come out of the international break with a home fixture against an AC Milan side that many had tipped for Scudetto success after a lavish off-season of spending.
However, Sarri's side have emerged from the pack to be early frontrunners and Mertens believes that could stand them in good stead, despite the loss of two key players to long-term knee injuries.
"We hope so. It's true we've been unlucky with Arek Milik's injury and now Faouzi Ghoulam," he added.
"We know that we don't have 30 men to count on, but we want to do well and are still ahead of the other teams.
"Believe me, that is already a huge advantage in a campaign that will be hard-fought."