Great Britain's Shannon Courtenay produced a fiercely determined performance to beat Ebanie Bridges in an enthralling fight and become a world champion for the first time.
Courtenay was bloodied from early on but a swelling over Australian Bridges' left eye proved key late in the fight.
It allowed Courtenay to produce a huge ninth round and finish strongly.
The cards read 97-94 98-92 98-92 to give an emotional Courtenay the vacant WBA world bantamweight title.
It was a bout 5 Live boxing analyst Steve Bunce said "might have been the best women's fight we've ever seen in this country".
The margin of the unanimous points win was harsh on Bridges but, on hearing her name read, 27-year-old Courtenay - who entered boxing when she turned her back on a party lifestyle in order to lose weight - screamed with delight.
"I can't put it into words - unbelievable," the Watford fighter said. "We worked so hard and for someone who has genuinely turned her life around it shows people can achieve anything.
"I boxed nicer, I had the cuter shots. I kept throwing the jab out. My jab won me the fight - you could see that from her eye."
Much of the fight's build-up had focused on Courtenay's criticism of Bridges' decision to market herself by turning out at recent weigh-ins wearing lingerie.
Bridges, 34, was accused of "flaunting her body" but the maths teacher from New South Wales showed her fighting spirit from the off by pressuring Courtenay with a rugged, come-forward style.
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Courtenay tried to box at range but was repeatedly drawn into a fight and the back-and-forth nature of the affair at London's Copper Box Arena created one of the most eye-catching bouts of 2021.
A beautifully timed right hand from Courtenay saw Bridges bend at the knees in the fifth but each time she faced adversity she fought doggedly in response, and she landed a fine right hand of her own in the seventh.
However, the swelling over her left eye progressively worsened and, after Courtenay fired home shot after shot in the ninth, Bridges told her corner that she could not see out of it.
Courtenay, who took shots throughout and showed her growing maturity by remaining poised while cut, unloaded more good work to close the affair with momentum.
She now appears set to face compatriot Rachel Ball - who inflicted her only defeat in August - but can first bask in the glory of world-title status earned in a way that underlined her natural fighting spirit.
Women's boxing shows its level
British trainer Dave Coldwell: As a fight, Courtenay v Bridges was another great advert for the women's game. Women's boxing has really blown up during behind closed doors boxing. It will be great to see fights like these in front of crowds with a real fight night atmosphere.
WBO world cruiserweight champion Lawrence Okolie: I enjoyed the Courtenay v Bridges fight so much! Women's boxing continuing to boom!
Marshall dominates to win again
Elsewhere, Britain's Savannah Marshall made easy work of her WBO world middleweight title defence against late stand-in Maria Lindberg.
Sweden's Lindberg - a four-time world-title challenger - took the contest at less than a week's notice and, after being floored in the second round, the 44-year-old could not climb from the canvas when down again in the third.
It was an effortless and destructive display from Marshall and, after her 10th win in as many fights, she said she now hoped to face American two-time Olympic champion Claressa Shields, who holds the other three world titles at middleweight.
"I punch too hard for Claressa Shields," Marshall, 29, said. "She's not interested and doesn't want to know.
"She'd much rather call out Katie Taylor, who is four weight classes below her. I'm not going to wait around.
"The utmost respect for Maria. I am grateful she stepped in. Sunday it looked like I wasn't even fighting. A change of opponent is hard to take when you've trained for weeks on a certain style. I didn't think it would go like that and I'm over the moon with it."