Napoli coach Carlo Ancelotti is pleased with Lorenzo Insigne's preseason form.
Inzaghi struck in the 3-0 defeat of Liverpool on Sunday.
Ancelotti said, "In an attacking sense, Insigne must take the initiative like he did against Liverpool. I have to congratulate Mertens and Insigne for their defensive work. They did a crucial job.
“Lorenzo looked like the Lorenzo before his problems last season. Now he's back. This Insigne is crucial for us when he plays like this.
“For us, Callejon's a resource. He always does everything with a manic level of application, so he can also play as a central midfielder.
“I tried him in the position for 15 minutes, but it was as if he'd been playing there for 15 years."