De Bruyne marked the occasion with a goal and a characteristically honest post-match reflection as Belgium reached the World Cup last 32, with his Napoli teammates Scott McTominay and David Neres also drawing transfer attention ahead of the knockout rounds.
Leandro Trossard struck twice for Belgium — on 28 and 50 minutes — before De Bruyne added a third on 66. New Zealand pulled one back through Elijah Just on 84 minutes before Romelu Lukaku and Alexis Saelemaekers rounded out a comfortable win in the final stages.
De Bruyne addressed the criticism directed at Belgium's experienced players, the difficulties of his debut season at Napoli, and the scale of what achieving a positive result meant against a backdrop of hard work.
"It was simply fun," De Bruyne said. "I just had my ninth wedding anniversary. My wife and children had told me I would score.
"They made a great effort to be here. Last year there were many challenges at Napoli. We all worked very hard. It's nice to be able to share this feeling with them. Even though now it was only my wife and sister-in-law, not the children."
He acknowledged the difficult opening two group games, against Egypt and Iran, in which Belgium had failed to find their best form.
"Everyone wants to play offensive football, create lots of chances and score," he said. "In the first games against Egypt and Iran we didn't manage to do that. There were options, but the timing wasn't right. Now it was. Though for a while I thought it would be another evening like that. Also for me. I was often in the right position, but things weren't going the right way."
De Bruyne confronted the scrutiny of Belgium's senior players directly.
"Because of the careers many Belgian players have had, our expectations are always very high," he said. "I also realise I will never again be the Kevin of nine years ago. That is normal. But I know how much work I am doing to be here at this World Cup and to perform at the highest possible level. I am proud of that. In the 16 years I have played for Belgium, I have always done everything to make this team win. We have had many positive moments, but also less good ones. That is part of the job. Now we knew we had to do better than in the first games against Iran and Egypt. We managed it."
He closed by framing the result as a starting point rather than a destination.
"We must keep our feet on the ground," he said. "We are happy, but saying it is a celebration after this victory... We simply knew we were not at our best and had to change things. Now it is only the beginning. Another knockout tournament. It will be all or nothing. So we must rest well, prepare well and hopefully be ready for the round of 32."
While De Bruyne was focused on Belgium's tournament, back in Naples the transfer window has brought Napoli into focus too.
According to Il Mattino, Portuguese clubs have registered an interest in David Neres, while Real Madrid and new head coach José Mourinho are reported to be keeping an eye on McTominay, whose combination of defensive and offensive contribution has made him one of the most valuable midfielders in Serie A.
McTominay is understood to want to remain at Napoli, who begin next season under Massimiliano Allegri following the departure of Antonio Conte.