The Belgian winger knows that if he impresses with the Partenopei, it will lift his hopes of earning a place in Marc Wilmots' squad for Brazil 2014
The 26-year-old winger joined the Partenopei from PSV during the summer and has made a decent start to life at the San Paolo, racking up one goal in seven appearances thus far.
However, he is determined to nail down a regular berth in Rafael Benitez's starting line-up in a bid to do all he can to secure inclusion in Marc Wilmots' panel for Brazil.
"I hope to do well here, because only by doing so can I collect caps for my national team and hope to be in the squad for the World Cup," Mertens told 'Radio Kiss Kiss.
Consequently, Mertens is thrilled that he has the full support of Napoli boss Benitez, who has the San Paolo side in third place in Serie A, just five points behind leaders Roma.
"For me, he is a great coach," he enthused. "He wanted me here, but I also really wanted to come and play in Italy.
"But, now, we're all just focused for the game tomorrow [Saturday] against Catania. We want to pick up three points.
"It's not the most important moment of the season, but it certainly is very delicate. We must have the same concentration we showed against Fiorentina [in midweek]."