The 37-year-old mother-of-two, who is battling stage 4 cancer, will sing the national anthem at State of Origin III, which is coming to Newcastle in NSW's Hunter Valley, due to the continued lockdown in Sydney.

Amanda, who has performed at community and sporting events since she was a child, announced her mission to perform the anthem at the game on social media on Wednesday night.

Less than 24 hours later, after her post was shared more than 600 times and picked up by numerous local media outlets, NRL officials reached out to Amanda to offer her the opportunity of a lifetime.

"I cannot believe it... I ugly cried and cried," she said.

"I'm so honoured and blessed.

"I've had the most gorgeous call from my favourite nurses at the Mater all cheering in the background.

"My boys are beyond thrilled."

EARLIER: Singing the national anthem at State of Origin has been a lifelong dream for Amanda Barrass.

The 37-year-old mother-of-two from Abermain, in NSW's Hunter Valley, is battling stage 4 cancer, and has made it her mission to belt out Advance Australia Fair at McDonald Jones Stadium next Wednesday night.

Amanda's talent is well-known in the Cessnock and Kurri Kurri communities, where she has been performing at local events since she was a child, and later as part of The Lanesbury Sisters duo with her sister Kristen.

Amanda is no stranger to singing the national anthem at sporting events - she has proudly sung for the Kurri Kurri Bulldogs on numerous occasions, performed at the Newcastle Rugby League grand final for six years, and had the honour of singing at the Matildas vs Chile game at McDonald Jones Stadium in 2018.

She has also been a featured performer at the Kurri Kurri Nostalgia Festival (performing tributes to Marilyn Monroe and Doris Day), and in 2014 was named Mrs Planet Australia at a quest that raised awareness of ovarian cancer.

Amanda was first diagnosed with breast cancer in 2016, and metastatic breast cancer of the bone two years later, having part of her spine removed after the cancer had eaten through her C7 vertebrae.

Since then, she and her husband Mark have set to out make special memories with their sons Rhys, 13, and Evan, 12.

Performing at the biggest game of the year, right in here in the Hunter, would be the perfect chance to create such a memory.

"It's things you can't put a price on," she said.

"Because I did most of my singing before they were born, they don't have that many memories of me singing.

"So to be able to give that to them for the rest of their life would be just incredible."

IN OTHER NEWS:

Amanda took to social media on Wednesday night to announce her mission.

"I put up a small post on Wednesday afternoon saying I must get Origin tickets, and if they want me to sing I'm free, making a joke out of it. But then I thought, I should put in a bit more effort."

By Thursday morning her post - including a video of her rousing rendition at the Matildas game - had been shared more than 600 times on Facebook, and she had been interviewed on two local radio stations.

While she hasn't heard from the NRL's powers-that-be by the time the Mercury went to press, if she does get a call-up for Origin night, it would be a highlight of her life.

"You just can't get anything better, especially coming from a rugby league-orientated town and family," she said.

"I've got all my fingers crossed."