Speaking to the Otago Daily Times after making it as far as the Wimbledon quarterfinals this week, Sun said she decided to make the switch after playing in Auckland following the Covid-19 pandemic and feeling love from the crowd.
"For the first time, I really felt the energy from the supporters and the crowd and it was such an amazing experience. I wasn’t playing for New Zealand but they supported me because they knew I was born in New Zealand and I was grateful for that."
Sun said she also made the decision because she observed that tennis in New Zealand could "grow and develop into something better and bigger, and it could benefit, I dunno, from seeing someone — could be anyone — on the big stage. It can bring inspiration to the country and to people who don’t know about tennis."
Sun was born near the Fiordland town of Te Anau and spent part of her childhood and teen years there, working on her fitness by tramping and running. She still visits the Fiordland family farm owned by her extended family and earlier this year was in the local park run.
When asked if she switched allegiance from Switzerland to New Zealand because of the Olympics, she said it "wasn’t that — that was a by-product".
"She is a really great athlete and her serve is super powerful. It would be interesting to play against her and she obviously has a powerful game and is such a nice person."
The two have already practised together.
Te Anau tennis club president Greg Shepherd said Sun’s achievements and commitment to New Zealand meant a lot to the club. Sun was an "incredible human".
"It is like she has been playing tennis for 100 years.
"She doesn’t seem to get flustered by anything. She’ll hit a duff shot, which is bound to happen every now and again with her style of play which is super aggressive, but then some people would be smashing rackets but not Lulu. She just keeps trying for a big shot and eventually it works and it is impressive to watch."
"She is so humble and we love her and can’t wait for her to come back and visit us and sign some signatures. She is a typical Te Anau-er — relaxed, chilled out, super friendly and really nice.
"She is one of us. She should come back here. I feel we are the most famous tennis club in the world at the moment."
"Young people will look at this and say maybe we can succeed too, even though we are in a small town. It is inspiring."