Claressa Shields and Savannah Marshall have been rivals since their amateur daysClaressa Shields became undisputed middleweight champion by beating long-time rival Savannah Marshall via unanimous decision in London.
The American was sensational in a career-best performance, avenging the only defeat on her pro and amateur record and staking her claim as one of the best fighters in the world.
All three judges saw it in Shields' favour - 96-96, 97-93, 97-93 - as she claimed the WBA, IBF, WBO, WBC and Ring Magazine titles on a historic night for women's boxing.
Both women paid tribute to each other and touted a potential rematch after a night of firsts at the O2 Arena.
The fight, which was 10 years in the making, was the first time two female boxers had headlined at a major venue in the UK.
It was a fascinating fight full of action and edge-of-your-seat exchanges as Marshall showed incredible heart and resolve to stay a constant threat.
It was billed as the biggest fight in women's history and could quickly turn into one of the greatest rivalries in boxing history if fans are treated to a second and even third fight.
It was also a fight of the year contender, the perfect follow-up to Katie Taylor and Amanda Serrano's remarkable encounter in April at Madison Square Garden that was another massive leap forward for women's boxing.
In the space of six months the female code has produced two undisputed fights contested by elite champions, sell-outs at major venues at opposite ends of the world and two fight of the year contenders.
Shields was emotional in her post-fight speech, but beamed with joy as she insisted the night did not just belong to her.
"It's not just a special moment for me, but it's a special moment for women's boxing, Savannah Marshall, Alycia Baumgardner, Mikaela Mayer, Caroline Dubois," Shields said.
"Women's boxing has been around for so many years and so many greats that came before us, but here we are in front of 20,000 fans in London at the O2 Arena and I think that's fight of the year.
"I'm just so happy and it's an unbelievable moment."
Shields proves GWOAT pedigree
Shields is still only 27 years oldShields' confidence was never in doubt. The self-proclaimed GWOAT - greatest woman fighter of all time - took part in a dance routine during her walk-out.
She soaked up the pressure and the boos of the sold-out 20,000-seater O2 arena, revelling in an occasion that at one time in her illustrious career she must have thought might never come.
The fight opened with a furious two minutes with Shields pouring on the pressure with shots to the body and head of 31-year-old Marshall.
The big puncher was repeatedly caught by the lightning pace of Shields' counters and when she tried to stamp her authority in the second, she was caught by two uppercuts from the two-time Olympic champion.
Shields was happy to be backed onto the ropes by Marshall, responding with fast counters over her rival's jab when the opportunities presented itself.
And the openings did come as Marshall tried to sap the energy out of the American with constant pressure.
Marshall's face and ears reddened more with every passing minute and Shields landed a superb left hook in the final seconds of the fourth round.
Shields refers to herself as the 'GWOAT'Shields and Marshall exchanged left hooks in the fifth round almost simultaneously in an eye-catching moment, but neither woman showed any sign of pain.
But there was damage inflicted - as Shields admitted afterwards, she could not see out of her right eye in the sixth and seventh round after a big shot from Marshall.
Regardless, the relentless pace continued and the precision and speed of Shields saw her land two right hands in quick succession.
Marshall's chin stood up to the challenge and the Briton was serenaded by the home crowd in the eighth round as she searched for a spark.
But again Shields produced the best shots in the final seconds, appearing to hurt Marshall momentarily with a parade of punches.
A cut appeared on the forehead of Shields, but the 12-time world champion remained just out of Marshall's reach.
"You can do it, you've got four minutes, dig deep, let her have it," was the rallying call from Marshall's trainer Peter Fury in the corner before the penultimate round.
Marshall tried to answer the call from her head coach, but the 31-year-old struggled to find a way through the Shields' defence even in a frantic finale which saw both women swinging.
Marshall was visibly gutted as she suffered the first loss of her pro career and handed over her WBO title to her most bitter rival, but the Briton was gracious, accepting defeat against a fighter who lived up to every inch of her moniker.
"She has definitely earned the title of the GWOAT," she said of Shields.
