Holly Holm pulled off a stunning upset over Ronda Rousey in the mixed martial arts championship, UFC 193.
She knocked the women's bantamweight champion out in the second round with a powerful kick to the head in Melbourne, Australia.
Ronda Rousey, 28, was undefeated in her first 12 mixed martial arts fights with 11 wins in the first round.
Holly Holm ended that run in front of a record Ultimate Fighting Championship crowd of around 75,000 fans.
The fight started quickly at the Etihad Arena, with 34-year-old Holly Holm landing some powerful shots to her opponent's head.
It left the champion with a bloody nose at the end of the first round.
Ronda Rousey then attempted to dominate the second round, pushing Holly Holm around the ring until the challenger snapped a massive kick to the head that instantly dropped her opponent to the canvas.
Holly Holm jumped on Ronda Rousey and hit her in the head several times before the referee stopped the fight.
An ecstatic Holm jumped around the ring as Rousey received medical treatment.
"I had so much love and support I just thought, 'How can I not do this?'" Holly Holm said from the ring. "This right here is priceless."
Ronda Rousey, a former judo Olympian, was unbeaten in 12 UFC fights before meeting Holly Holm.
A win would have been her seventh title defence.
Instead, veteran female boxer Holly Holm, from the US state of New Mexico, now has the championship belt.
"I have to say that everything that we worked on presented itself in the fight," said Holly Holm.
"Every grab that she tried to get and clinch on the cage, and I just had help with everything.
"I have not spent this much time in the gym before any fight of my life."
The UFC brought its showcase UFC 193 to Australia, with the Ronda Rousey-Holly Holm fight overshadowing the men as the main event.
Organizers announced a crowd of 56,214 at Melbourne's Etihad Stadium, which normally hosts Aussie rules football matches.
That beat the 55,724 fans who attended UFC 129 at Toronto's Rogers Centre in 2011.
Ronda Rousey left the stadium to receive treatment for concussion and facial cuts at a nearby hospital after the loss and missed the post-fight media conference.
UFC chief Dana White said a rematch between the two "made a lot of sense".
"Obviously we don't make fights the night of the fight, but the rematch makes a lot of sense," he said. "The rematch is what the people want to see."