Claressa Shields has compared her greatness to Muhammad Ali and claimed "98 per cent of men in the world can't beat me".
History-making Shields is aiming to further her legacy by winning an undisputed championship in a second weight division when she fights Marie-Eve Dicaire on Friday for every major super-welterweight belt.
She became the first American boxer (male or female) to win gold medals at consecutive Olympics then earned the records for becoming a two and three-weight world champion in the fewest professional fights.
Shields calls herself the 'GWOAT' (Greatest Woman of All Time) - she has been outspoken on social issues such as George Floyd's death and, more recently, the gender pay-gap in women's boxing.
Her latest powerful speech, before the fight against Dicaire, was: "I don't box for a hobby. It's not a hobby. It's my career, and I feel like people underestimate me when I speak about how great I am.
"But if I didn't say how great I am, no one in this room would have ever called me great because they don't recognise it. Only the greats know that they're great.
"Like Muhammad Ali. Nobody called him the greatest of all time. They actually called him the 'Louisville Lip' because he talked too much.
"If he had never said he was the greatest of all time, he would have never been considered the greatest. No matter what boxer comes along, nobody can get in front of Muhammad Ali. That's how I feel about myself.
"Muhammad Ali is first, and Claressa Shields is second. I am the greatest woman of all time, and 98 per cent of men in the world can't beat me.
"I want you to know I'm not taking prisoners. This is a new era for me. My name from now on is Claressa 'The GWOAT' Shields. [Previous nickname] 'T-Rex' has long gone. 'T-Rex' was aggressive, but the greatest of all time has so much more. She possesses poise, power, and punch placement.
"In an interview, I saw [Dicaire] is not worried about the outcome; she's worried about the task. Well, I'm worried about the outcome. I've known what the task is for the last 13 months.
"I'm concerned about the outcome because I don't particularly appreciate losing. When I lost my first fight when I was 17, I didn't sleep until I was 21 when I won my second Olympics. That's how personally I take this fight.
"I'm hoping she can bring out a different side of me because many girls haven't been able to take me to level three. I'm hoping she can take me to level 10."
Shields vs Marshall rematch?
The amateur defeat when Shields was 17 came against Britain's Savannah Marshall who, last October, became WBO middleweight champion.
Marshall dished out a one-sided stoppage of Hannah Rankin, an opponent who had gone the distance with Shields.
Shields previously told Sky Sports about settling the score with Marshall: "Savannah isn't a better fighter than me, and that's been proven.
"It is so sad for her that she wanted to wait for my belt to become vacant, rather than fight me for it.
"That's so soft.
"She could have fought for all the belts at 160lbs to show how tough she really is.
"Savannah's coach Peter Fury said she's too strong for me? Shut up, shut up!
"Savannah hasn't been challenged enough yet for her to even be saying my name.
"But if she wants to come see me? Then come see me. I'll shut her and her team up because they do too much talking for me!"
Importance of an all-female fight night
Shields is headlining in her hometown of Flint, Michigan, on Friday and is significantly topping an all-female card of fights.
Danielle Perkins, the former basketball professional who survived a coma and the trauma of a car accident to now become a heavyweight force, is in action against Monika Harrison.
"It's important for equality across the board," Perkins told Sky Sports. "We need to have a female heavyweight division for the Tyson Furys, the Anthony Joshuas, the Deontay Wilders."