Jenkins, who trains Maea twice a week, is confident she will win and said her "special left shot" will be one to watch.
"Maea is a fantastic boxer and we have been working hard ahead of this fight so I'm feeling very positive," he said.
"She has a wonderfully educated left shot for her age, which hard work and dedication has perfected - I think that will make a real difference in the ring.
"Every week Maea trains very hard and she moves very quickly which is difficult to compete against ... She is definitely one to watch out for in the future and if she puts the hard work in the sky is the limit."
Maea, one of 11 children, took up the sport to help boost her confidence which was affecting her in all areas of life, particularly at school.
The fifth oldest among her siblings, she took to boxing immediately and has high aspirations for the future.
"I have always been very shy and I didn't want to get bullied at school because it can be really tough sometimes," Maea said.
"I didn't feel very confident and it wasn't nice feeling like that all the time. But my family have been great and they encouraged me to take up boxing.
"As soon as I put the gloves on I loved it. It gives me a real rush stepping in the ring ... My best shot is definitely my left jab and in the future I want to be a professional. It will take a lot of hard work but it's what I want to do."
Father Hamish Hay is impressed with his daughter's transformation and believes the discipline teaches courage and perseverance.
"As a female I wanted Maea to be able to take care of herself and not have to rely on anyone. Also in school it can be really tough for kids when they get pushed around," he said. "Some would question letting Maea do boxing but it has done her the world of good. She is more confident and happy.
"It has made her brave, fearless and hard-working - all valuable life qualities.
"I'm really impressed, Maea is now a mean machine and all the family are all behind her cheering her on."
Today 22 boxing clubs will converge on Selwyn Primary School for the one-day event.
It will very much be a family affair for the Hays, as younger son Kevin is up against fellow 10-year-old Kahu Rangiawhau, and both are trained by Jenkins.
Two more of Jenkins' boxers from Rotorua Central Boxing Club will compete - Jonathan Tewhau, 21 will compete in the elite male 91kg category, , while sister Amanda will be fighting it out in the elite female 57kg division.
The Central North Island Amateur Boxing Championships start at 1pm and tickets are available on the door. For more information visit www.boxingnz.org.nz
Profile
Name: Maea Hay
Age: 12 (fights U14 level)
Weight category: 48kg
Fight record: 10 wins/ two losses
2016 record: unbeaten - four wins
Best shot: left jab
Next opponent: Mya Kahukoti, Gisborne
Trainer: Rex Jenkins
