An injury to Shanell Dargan's back serious enough for other boxers to call off a scheduled bout just weeks out had threatened to end her dream title fight, but the new world champion's spirit would not be denied.

The 32-year-old stunned Shannon O'Connell inside just two rounds for a technical knockout win for the vacant IBF International Bantamweight belt at The Star Sydney casino on Thursday night.

The triumph skyrocketed Darnell up the world rankings of the top 10 fighters under the 54-kilogram female weight category.

"To be honest, I was planning on a 10-round war," Dargan told National Indigenous Times.

"I knew Shannon was tough, but I just did everything right and I knew in my training how strong I felt and the power that I possessed could be too much for her to handle.

"On paper, I shouldn't have been able to beat her.

"I think she may have underestimated me a bit, but what I have internally inside of me is a will to win because I have been struggling my whole life and this was always going to help me get out of tough things I went through when I was younger."

Overcoming a serious injury

But doubts on the main event were first raised three weeks out from the Wiradjuri and Mununjali woman's biggest fight of her career, straining the lumbosacral joint, the lowest and most crucial part of the spine that connects the last two vertebrae. The joint acts as a major transitional point for transferring weight through the pelvis bone when throwing forward punches.

"I had a pretty bad injury when I pulled my L4, L5-S1 where I had to go to the physio like every second day to try and get it working," Dargan said.

"That was a bit scary, first because when I did my back, I could hardly walk and move, but just with perseverance and listening to my physio and to my body, I made sure that I did absolutely everything that was asked of me.

"I had to adapt with my training and accept things with my strength and conditioning, but I was able to get going again.

"At the start, my physio said, 'Look, we're just trying to manage it for now - you're not going to be 100 percent'.

"She said 'we'll get you there' but she also wanted me to get an MRI to assess the damage."

Dargan, who claimed a sixth straight win after scoring just one victory in her first four professional contests which included two draws, has since won eight from the last nine times she has stepped between the ropes.

That type of tenacity to fight back from adversity was enough to suggest to her physiotherapist there was no throwing in the towel despite suffering the injury so close to the massive 10-bout card.

"I said to her that once I am in the ring, it all doesn't matter and if it hurts a lot after, I don't care," Dargan said.

"Just as long I am right when I am in there. In the ring, I did not think about it once - it was never in my thoughts.

"I am a fighter and I just knew I wasn't going to give it up."

Inspired by her young son

The expectations outweighed the repercussions the moment an official clipped the belt around her waist, Dargan glancing to her left and smiling down at her nine-year-old son, Oryn, who was at full stretch proudly holding up the Aboriginal flag.

Dargan said the moment was about pride in their culture, but also a life lesson to inspire Oryn - a budding soccer junior - to seize his own dreams.

"It was a bit of a we-did-it moment," Dargan said.

"People ask me 'what's your why' and I say my little boy... Without him, his love and my love for him, I wouldn't be where I am today."

Dargan's remarkable story includes surviving domestic violence, and pursuing music through The Voice series.

She only took up boxing at 26, not long after becoming a newly single mum.

"He was a one-year-old when I first walked into a boxing gym," Dargan said of Oryn.

"We were going through a hard time, and I looked at him every day and I thought I am going to make something with my life. He's been the biggest motivation for me."

The journey was about starting from the bottom and working her way up through the ranks.

Before even lacing up a boxing glove, she had lived through the heartbreak of having both of her parents battling addictions and spending time in prison growing up.

"I remember lying once, crying my eyes out thinking, 'Where is my life - what has it come to?'," she said.

"I was feeling that I failed as a person and as a mum.

"Now looking back to see how far I've come is truly special."

Respect for her opponent

Dargan, who also has strong Irish heritage, paid respect to O'Connell - a boxer she has always admired.

"I have always thought she was such a beast, so this is a full-circle moment," she said.

"You see this lady I was in awe of, and I am in the ring with her and now beating her. It's a crazy feeling and I knew there was a lot of doubters to that.

"But the past 12 months, we have put in the hardest work ever my team. There was a lot of tears with that and a lot of times I was like 'am I cut out for this?'."

The moment referee Will Soulos stopped the contest and waived O'Connell away, a stark reality for Dargan slowly started to set in.

But the sport represents far more than titles or prize money. It's about her values and character. Days after the fight she said several young women have reached out asking for advice fighting against their own adversity, while sharing a tough life story.

"If I can help just one person change their life, that means a lot more in this world than winning titles," she said.

"I just want to prove that you can do anything if you put your mind to it."