Claressa Shields v Savannah Marshall: Origins of a 10-year feud unlikely to end on Saturday night

They have known each other for a while.

American Shields was 17 when they met Marshall was 21. The London 2012 Olympics were weeks away when they were both rising stars.

They have become bitter rivals over the course of a decade.

Tensions rise when Shields enters Marshall's room. The pair are kept apart, ushered into different events at different times, and meet briefly for a face-off.

The rivalry is unlikely to be put to bed on Saturday, but how did it start? Why hasn't it stopped yet? Is it a real fight or hype for the cameras?

First meeting in China

They met for the first time in 2012 at the AIBA world championships.

Everyone was talking about a young American that had never been beaten. Marshall remembers that she was the next star.

Marshall was getting ready for the Olympics while Shields was trying to get into the Olympics. It was only the second international tournament Shields had competed in and she was fresh off a shock win against three-time world champion Mary Spencer.

They were drawn to fight each other. She remembers that her coach looked at her.

Women's boxing folklore says that the two women fought in a fight. Marshall won the game on points. She says she won by a wide margin.

A current world champion and a USA team-mate of Shields remembers the match.

She remembers keeping the perfect space away from the other. I didn't let her close that space and let her hold it. The fight ended in those three rounds.

Marshall thinks that the only loss of Shields' fighting career is the one she suffered. Marshall and Shields both won gold at the Olympics. Their rivalry was based on this.

Shields doesn't care about the loss in the amateurs.

I will show everyone that I'm better than her now.

Sparring stories & different amateur paths

Four years after their first meeting, Marshall traveled with Team Great Britain to Colorado to train for the Rio Olympics.

Marshall and Shields were the only females. Shields was the gold medal winner at the Olympics.

They sparred at the end of the camp.

Marshall says nothing happened.

Shields said that he pulverised her for four rounds.

The rival's amateur careers were very different. Marshall stumbled frequently while Shields won every amateur championship she entered.

She was knocked out of her home Olympics in London in the first round. Marshall contemplated walking away from the sport after Shields excelled.

Rivalry repackaged for the pro game

Shields became a pro in 2016 She became a paid employee a year later.

Marshall was snapped up by a promotional company. The lure of a burgeoning pro game and the support of Floyd Mayweather was too much to refuse.

There was a lot of interest in Marshall's relationship with Shields. The rivalry for the pro game could be re-package.

Marshall signed with Eddie Hearn's Matchroom in the fall of 2019. Shields had already won world titles in two weights and was the undisputed champion.

There was a plan to hyping a second fight. It was obvious that Shields and Marshall would meet again.

Timing was off, and it would not be until 2021 when Marshall linked up with promoter Ben Shalom and Boxxer that the promises of a second fight finally came to fruition.

Shields signed with Boxxer and Sky Sports.

She watched from the ring as Marshall defeated Femke Hermans in the third round.

I was the top player in the amateur league. Shields said that he lost one time. There wasn't ever a rivalry. It's not true.

It's possible to live off the amateurs in the pros. I'm not living there. I decided to become a pro.

I'm the only boxer who's ever won two undisputed titles. There has never been a man that did that.

I don't want to brag but that is the truth. She told everyone that she beat me up in the amateurs. She is superior to me. I had to get to the belts first. Everybody believed this.

It was an easy fight to win, according to Shalom.

The stage was set for two of the best in the women's game to go toe-to-toe after a series of delays.

'We clash massively' - Opposites attract and collide

Shields and Marshall are not the same person. Their personality is not the same as their sense of hard work and loyalty.

Shields would not shy away from a fight with the Pope if he questioned her fighting abilities.

Marshall has struggled with shyness throughout her career and only recently has her quiet confidence come back.

We fight a lot. I've known her for many years. Marshall admits to giving up trying to crack that code.

She might be trying to play the baddie or she might be not wired right.

Shields and Marshall have a history of fighting. The one that stood out was after Shields' most recent victory. Marshall pretended to sleep at ringside as the American erupted.

Energy was carried through until fight night because of the ins and outs between the two. They have made fun of each other on social media and at press conferences.

Their differences will be resolved in the ring. A close fight could lead to a second fight. On fight night, the rivalry is likely to continue.

I don't want to be friends with her. I want to win a world title. I've trained so I'm confident. Shields says that the work he has put in will be popping.

Marshall says it's all a big deal. She's here because of me, that's right. She cannot sell a ticket. The average person on the street could be asked who Shields is. Her face should be on a box of cereals.

I respect the woman. She has done a lot for the sport. She rubs people the wrong way.

I'm not dumb. I am aware of what she has done. That cannot be ignored.