The teenager was on target twice at the Academy Stadium during the 3-1 win over the Italian side, while team mate Benjamin Garre netted the other.
In their next fixture, City host the Rams in the Premier League 2 and Diaz is focused on the game ahead.
“Of course [it will give the team a confidence boost], but now it’s another game,” he explained after the Napoli match.
“Now this game has passed and we need to focus on the next one, but of course it’s always good to get that win before another game.”
When asked about his two goals the Spaniard preferred to praise the team’s performance, adding: “The best thing is the three points.
“It’s always good to score goals but now, it’s about the team and the team played really well so I’m happy.
“Napoli is a good team, they’re strong and they tackle and tackle so I think we moved the ball really quickly,” Diaz added. “We played our way.”
City EDS face Derby at the Academy Stadium on Saturday 21 October at 11am.
Tickets are on sale now and available to purchase from mancity.com/tickets, while Seasoncard holders and Cityzens Matchday members are able to claim a free ticket to this game.
