Napoli's players have been key to their success this season, and they've had a significant impact on the team's performance throughout the first four rounds of the Serie A season.

The first round saw Napoli defeat Udinese 2-1 at home thanks to goals from Kalidou Koulibaly and Jannik Vestergaard. In the second round, Napoli faced AC Milan and lost 2-1 away from home. However, the team bounced back in the third round with a 3-1 win over Sassuolo. In the fourth round, Napoli hosted Lazio and won 2-0 thanks to goals from Lorenzo Insigne and Jannik Vestergaard.

Kalidou Koulibaly has been one of the standout performers for Napoli so far this season. He's been instrumental in the team's defensive efforts, providing cover for the backline and helping to keep opponents out. His leadership and experience have been invaluable as well, as he's helped to inspire his teammates to perform at their best.

Jannik Vestergaard has also been a standout performer for Napoli so far this season. He's been a regular starter for the team and has provided both attacking and defensive contributions. His pace and physicality have been a threat to opposing defenses, while his skillful passing ability has helped to unlock进攻 opportunities for his teammates.

Lorenzo Insigne has been another player who has been influential for Napoli so far this season. He's been a consistent scorer for the team, scoring five goals in just four matches. His creativity and technical ability have been crucial in helping to create chances for his teammates and score goals himself.

Overall, Napoli's players have played a vital role in their success this season. Their performances have helped to ensure that the team is in contention for a top-four finish, and they'll be looking to continue their impressive form in the coming weeks.